diff --git a/quantlib/cashflows/_cashflows.pxd b/quantlib/cashflows/_cashflows.pxd
index b0173176b..d521f4971 100644
--- a/quantlib/cashflows/_cashflows.pxd
+++ b/quantlib/cashflows/_cashflows.pxd
@@ -1,11 +1,12 @@
 from libcpp cimport bool
 from libcpp.pair cimport pair
+from quantlib.ext cimport optional
 from quantlib.time._date cimport Date
 from quantlib.types cimport Rate, Real
 from quantlib.termstructures._yield_term_structure cimport YieldTermStructure
 from .._cashflow cimport Leg
 
-cdef extern from 'ql/cashflows/cashflows.hpp' namespace 'QuantLib':
+cdef extern from 'ql/cashflows/cashflows.hpp' namespace 'QuantLib' nogil:
     cdef cppclass CashFlows:
         @staticmethod
         Date startDate(const Leg& leg)
@@ -15,26 +16,26 @@ cdef extern from 'ql/cashflows/cashflows.hpp' namespace 'QuantLib':
 
         @staticmethod
         bool isExpired(const Leg& leg,
-                       bool includeSettlementDateFlows,
-                       Date settlementDate = Date())
+                       optional[bool] includeSettlementDateFlows, # = nullopt
+                       Date settlementDate) # = Date()
 
         @staticmethod
         Date previousCashFlowDate(const Leg& leg,
-                                  bool includeSettlementDateFlows,
+                                  optional[bool] includeSettlementDateFlows, # = nullopt
                                   Date settlementDate)# = Date())
 
         @staticmethod
         Date nextCashFlowDate(const Leg& leg,
-                              bool includeSettlementDateFlows,
+                              optional[bool] includeSettlementDateFlows, # = nullopt
                               Date settlementDate)# = Date())
 
         @staticmethod
         Real previousCashFlowAmount(const Leg& leg,
-                                   bool includeSettlementDateFlows,
-                                   Date settlementDate)# = Date())
+                                    optional[bool] includeSettlementDateFlows, # = nullopt
+                                    Date settlementDate)# = Date())
         @staticmethod
         Real nextCashFlowAmount(const Leg& leg,
-                                bool includeSettlementDateFlows,
+                                optional[bool] includeSettlementDateFlows, # = nullopt
                                 Date settlementDate)# = Date())
         # static Rate
         # previousCouponRate(const Leg& leg,
@@ -49,14 +50,14 @@ cdef extern from 'ql/cashflows/cashflows.hpp' namespace 'QuantLib':
         # nominal(const Leg& leg,
         #         bool includeSettlementDateFlows,
         #         Date settlDate = Date());
-        # static Date
-        # accrualStartDate(const Leg& leg,
-        #                  bool includeSettlementDateFlows,
-        #                  Date settlDate = Date());
-        # static Date
-        # accrualEndDate(const Leg& leg,
-        #                bool includeSettlementDateFlows,
-        #                Date settlementDate = Date());
+        @staticmethod
+        Date accrualStartDate(const Leg& leg,
+                              optional[bool] includeSettlementDateFlows, # = nullopt
+                              Date settlDate) # = Date()
+        @staticmethod
+        Date accrualEndDate(const Leg& leg,
+                            optional[bool] includeSettlementDateFlows, # = nullopt
+                            Date settlementDate) # = Date()
         # static Date
         # referencePeriodStart(const Leg& leg,
         #                      bool includeSettlementDateFlows,
@@ -69,39 +70,39 @@ cdef extern from 'ql/cashflows/cashflows.hpp' namespace 'QuantLib':
         # accrualPeriod(const Leg& leg,
         #               bool includeSettlementDateFlows,
         #               Date settlementDate = Date());
-        # static Date::serial_type
-        # accrualDays(const Leg& leg,
-        #             bool includeSettlementDateFlows,
-        #             Date settlementDate = Date());
+        @staticmethod
+        Date.serial_type accrualDays(const Leg& leg,
+                                     optional[bool] includeSettlementDateFlows, # = nullopt
+                                     Date settlementDate) # = Date()
         # static Time
         # accruedPeriod(const Leg& leg,
         #               bool includeSettlementDateFlows,
         #               Date settlementDate = Date());
-        # static Date::serial_type
-        # accruedDays(const Leg& leg,
-        #             bool includeSettlementDateFlows,
-        #             Date settlementDate = Date());
-        # static Real
-        # accruedAmount(const Leg& leg,
-        #               bool includeSettlementDateFlows,
-        #               Date settlementDate = Date());
+        @staticmethod
+        Date.serial_type accruedDays(const Leg& leg,
+                                     optional[bool] includeSettlementDateFlows, # = nullopt
+                                     Date settlementDate) # = Date()
+        @staticmethod
+        Real accruedAmount(const Leg& leg,
+                           optional[bool] includeSettlementDateFlows, # =nullopt
+                           Date settlementDate) # = Date()
         @staticmethod
         Real npv(const Leg& leg,
                  const YieldTermStructure& discountCurve,
-                 bool includeSettlementDateFlows,
+                 optional[bool] includeSettlementDateFlows, # = nullopt
                  Date settlementDate, # = Date(),
                  Date npvDate) # = Date())
 
         @staticmethod
         Real bps(const Leg& leg,
                  const YieldTermStructure& discountCurve,
-                 bool includeSettlementDateFlows,
+                 optional[bool] includeSettlementDateFlows, # = nullopt
                  Date settlementDate, # = Date(),
                  Date npvDate) # = Date())
 
         @staticmethod
         pair[Real, Real] npvbps(const Leg& leg,
                                 const YieldTermStructure& discountCurve,
-                                bool includeSettlementDateFlows,
+                                optional[bool] includeSettlementDateFlows, # = nullopt
                                 Date settlementDate, # = Date(),
                                 Date npvDate) #= Date())
diff --git a/quantlib/cashflows/_floating_rate_coupon.pxd b/quantlib/cashflows/_floating_rate_coupon.pxd
index ed1402694..2859840d9 100644
--- a/quantlib/cashflows/_floating_rate_coupon.pxd
+++ b/quantlib/cashflows/_floating_rate_coupon.pxd
@@ -1,11 +1,13 @@
 from quantlib.types cimport Natural, Rate, Real, Spread
 from libcpp cimport bool
 from quantlib.ext cimport shared_ptr
+from quantlib.handle cimport Handle
 from quantlib.time._date cimport Date
 from quantlib.time._daycounter cimport DayCounter
 from quantlib._cashflow cimport CashFlow
 from quantlib._interest_rate cimport InterestRate
 from quantlib.cashflows._coupon cimport Coupon
+from quantlib.termstructures._yield_term_structure cimport YieldTermStructure
 from ._coupon_pricer cimport FloatingRateCouponPricer
 from quantlib.indexes._interest_rate_index cimport InterestRateIndex
 
@@ -29,6 +31,7 @@ cdef extern from 'ql/cashflows/floatingratecoupon.hpp' namespace 'QuantLib' nogi
         Date fixingDate()
         Real gearing()
         Spread spread()
+        Real price(Handle[YieldTermStructure])
         Rate indexFixing()
         Rate convexityAdjustment() except +
         Rate adjustedFixing() except +
diff --git a/quantlib/cashflows/_overnight_indexed_coupon.pxd b/quantlib/cashflows/_overnight_indexed_coupon.pxd
index 91d226cff..c0aa631ba 100644
--- a/quantlib/cashflows/_overnight_indexed_coupon.pxd
+++ b/quantlib/cashflows/_overnight_indexed_coupon.pxd
@@ -2,8 +2,9 @@ from quantlib.types cimport Integer, Natural, Rate, Real, Spread, Time
 
 from libcpp cimport bool
 from libcpp.vector cimport vector
-from quantlib.ext cimport shared_ptr
+from quantlib.ext cimport shared_ptr, optional
 from quantlib.time._date cimport Date
+from quantlib.time._period cimport Period
 from quantlib.time._daycounter cimport DayCounter
 from quantlib.time._schedule cimport Schedule
 from quantlib.time._calendar cimport Calendar
@@ -11,6 +12,7 @@ from quantlib.time.businessdayconvention cimport BusinessDayConvention
 
 from quantlib.indexes._ibor_index cimport OvernightIndex
 from ._floating_rate_coupon cimport FloatingRateCoupon
+from ._overnight_indexed_coupon_pricer cimport OvernightIndexedCouponPricer
 from .rateaveraging cimport RateAveraging
 from .._cashflow cimport Leg
 
@@ -28,9 +30,11 @@ cdef extern from 'ql/cashflows/overnightindexedcoupon.hpp' namespace 'QuantLib'
                                const DayCounter& dayCounter, #= DayCounter(),
                                bool telescopicValueDates, #=False,
                                RateAveraging averagingMethod, # = RateAveraging::Compound
-                               Natural lookback_days,
-                               Natural lockout_days,
-                               bool apply_observation_shift)
+                               Natural lookback_days, # = Null<Natural>
+                               Natural lockout_days, # = 0
+                               bool apply_observation_shift, #+ False
+                               bool compound_spread, # = False
+                               )
 
         vector[Date]& fixingDates()
         vector[Time]& dt()
@@ -39,6 +43,10 @@ cdef extern from 'ql/cashflows/overnightindexedcoupon.hpp' namespace 'QuantLib'
         RateAveraging averagingMethod()
         Natural lockoutDays()
         bool applyObservationShift()
+        bool compoundSpreadDaily()
+        Real effectiveSpread()
+        Real effectiveIndexFixing()
+
 
     cdef cppclass OvernightLeg:
         OvernightLeg(Schedule schedule, shared_ptr[OvernightIndex] overnightIndex)
@@ -48,9 +56,25 @@ cdef extern from 'ql/cashflows/overnightindexedcoupon.hpp' namespace 'QuantLib'
         OvernightLeg& withPaymentCalendar(Calendar)
         OvernightLeg& withPaymentLag(Integer Lag)
         OvernightLeg& withSpreads(Real spread)
-        OvernightLeg& withObservationShift(bool)
+        OvernightLeg& withSpreads(const vector[Spread]& spreads)
+        OvernightLeg& withTelescopicValueDates(bool telescopicValueDates)
+        OvernightLeg& withAveragingMethod(RateAveraging averagingMethod)
         OvernightLeg& withLookbackDays(Natural)
         OvernightLeg& withLockoutDays(Natural)
+        OvernightLeg& withObservationShift(bool applyObservationShift) # = true);
+        OvernightLeg& compoundingSpreadDaily(bool compoundSpreadDaily) # = true);
+        OvernightLeg& withLookback(const Period& lookback)
+        OvernightLeg& withCaps(Rate cap)
+        OvernightLeg& withCaps(const vector[Rate]& caps)
+        OvernightLeg& withFloors(Rate floor)
+        OvernightLeg& withFloors(const vector[Rate]& floors);
+        OvernightLeg& withNakedOption(bool nakedOption)
+        OvernightLeg& withDailyCapFloor(bool dailyCapFloor) # = true);
+        OvernightLeg& inArrears(bool inArrears)
+        OvernightLeg& withLastRecentPeriod(const optional[Period]& lastRecentPeriod)
+        OvernightLeg& withLastRecentPeriodCalendar(const Calendar& lastRecentPeriodCalendar)
+        OvernightLeg& withPaymentDates(const vector[Date]& paymentDates)
+        OvernightLeg& withCouponPricer(const shared_ptr[OvernightIndexedCouponPricer]& couponPricer)
         Leg operator() const
 
 cdef extern from 'ql/cashflows/overnightindexedcoupon.hpp':
diff --git a/quantlib/cashflows/_overnight_indexed_coupon_pricer.pxd b/quantlib/cashflows/_overnight_indexed_coupon_pricer.pxd
index b79c368dc..e68c56de2 100644
--- a/quantlib/cashflows/_overnight_indexed_coupon_pricer.pxd
+++ b/quantlib/cashflows/_overnight_indexed_coupon_pricer.pxd
@@ -1,13 +1,21 @@
 from quantlib.types cimport Rate, Real
 from libcpp cimport bool
+from quantlib.handle cimport Handle
 from ._coupon_pricer cimport FloatingRateCouponPricer
+from quantlib.termstructures.volatility.optionlet._optionlet_volatility_structure cimport OptionletVolatilityStructure
 
 cdef extern from 'ql/cashflows/overnightindexedcouponpricer.hpp' namespace 'QuantLib' nogil:
-    cdef cppclass CompoundingOvernightIndexedCouponPricer(FloatingRateCouponPricer):
+
+    cdef cppclass OvernightIndexedCouponPricer(FloatingRateCouponPricer):
+        pass
+
+    cdef cppclass CompoundingOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
         pass
-    cdef cppclass ArithmeticAveragedOvernightIndexedCouponPricer(FloatingRateCouponPricer):
+    cdef cppclass ArithmeticAveragedOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
         ArithmeticAveragedOvernightIndexedCouponPricer(
             Real meanReversion, # = 0.03
             Real volatility, # = 0.00 No convexity adjustment by default
-            bool byApprox # = false, True to use Katsumi Takada approximation
+            bool byApprox, # = false, True to use Katsumi Takada approximation
+            Handle[OptionletVolatilityStructure] v, # = Handle[OptionletVolatilityStructure]()
+            const bool effective_volatility_input, # = False
         )
diff --git a/quantlib/cashflows/api.py b/quantlib/cashflows/api.py
index a554a163d..727d09b63 100644
--- a/quantlib/cashflows/api.py
+++ b/quantlib/cashflows/api.py
@@ -1,5 +1,7 @@
-from .overnight_indexed_coupon import OvernightIndexedCoupon, OvernightLeg
+from .overnight_indexed_coupon import OvernightIndexedCoupon, OvernightLeg, as_overnight_indexed_coupon
 from .cms_coupon import CmsCoupon
-from .ibor_coupon import IborCoupon
-from .fixed_rate_coupon import FixedRateCoupon, FixedRateLeg
+from .ibor_coupon import IborCoupon, as_ibor_coupon
+from .floating_rate_coupon import FloatingRateCoupon, as_floating_rate_coupon
+from .fixed_rate_coupon import FixedRateCoupon, FixedRateLeg, as_fixed_rate_coupon
 from ..cashflow import SimpleCashFlow, Leg
+from .cap_floored_coupon import CappedFlooredCoupon, as_capped_floored_coupon
diff --git a/quantlib/cashflows/cap_floored_coupon.pxd b/quantlib/cashflows/cap_floored_coupon.pxd
index 26af624d6..fb20d689c 100644
--- a/quantlib/cashflows/cap_floored_coupon.pxd
+++ b/quantlib/cashflows/cap_floored_coupon.pxd
@@ -2,7 +2,7 @@ from .floating_rate_coupon cimport FloatingRateCoupon
 from . cimport _cap_floored_coupon as _cfc
 
 cdef class CappedFlooredCoupon(FloatingRateCoupon):
-    cdef inline _cfc.CappedFlooredCoupon* as_ptr(self)
+    cdef inline _cfc.CappedFlooredCoupon* as_ptr(self) noexcept
 
 cdef class CappedFlooredIborCoupon(CappedFlooredCoupon):
     pass
diff --git a/quantlib/cashflows/cap_floored_coupon.pyx b/quantlib/cashflows/cap_floored_coupon.pyx
index 48cd4126c..6321d92bb 100644
--- a/quantlib/cashflows/cap_floored_coupon.pyx
+++ b/quantlib/cashflows/cap_floored_coupon.pyx
@@ -1,15 +1,15 @@
-include '../types.pxi'
+from quantlib.types cimport Natural, Rate, Real, Spread
 from libcpp cimport bool
 from cython.operator cimport dereference as deref
 from quantlib.utilities.null cimport Null
-from quantlib.ext cimport shared_ptr, static_pointer_cast
+from quantlib.ext cimport static_pointer_cast, dynamic_pointer_cast
 from quantlib.cashflows.coupon_pricer cimport FloatingRateCouponPricer
 from quantlib.indexes.ibor_index cimport IborIndex
 from quantlib.indexes.swap_index cimport SwapIndex
 from quantlib.time.date cimport Date, Period
 from quantlib.time.daycounter cimport DayCounter
 
-from .._cashflow cimport CashFlow
+from ..cashflow cimport CashFlow
 from . cimport _floating_rate_coupon as _frc
 cimport quantlib.indexes._ibor_index as _ii
 cimport quantlib.indexes._swap_index as _si
@@ -18,12 +18,15 @@ cdef class CappedFlooredCoupon(FloatingRateCoupon):
     def __init__(self, FloatingRateCoupon underlying not None,
                  Rate cap=Null[Real](),
                  Rate floor=Null[Real]()):
-        self._thisptr = shared_ptr[CashFlow](new _cfc.CappedFlooredCoupon(
-            static_pointer_cast[_frc.FloatingRateCoupon](underlying._thisptr),
-            cap,
-            floor))
+        self._thisptr.reset(
+            new _cfc.CappedFlooredCoupon(
+                static_pointer_cast[_frc.FloatingRateCoupon](underlying._thisptr),
+                cap,
+                floor
+            )
+        )
 
-    cdef inline _cfc.CappedFlooredCoupon* as_ptr(self):
+    cdef inline _cfc.CappedFlooredCoupon* as_ptr(self) noexcept:
         return <_cfc.CappedFlooredCoupon*>self._thisptr.get()
 
     @property
@@ -56,15 +59,22 @@ cdef class CappedFlooredCoupon(FloatingRateCoupon):
 
     @property
     def is_floored(self):
-        return (<_cfc.CappedFlooredCoupon*>self._thisptr.get()).isFloored()
+        return self.as_ptr().isFloored()
 
     @property
     def underlying(self):
         cdef FloatingRateCoupon instance = FloatingRateCoupon.__new__(FloatingRateCoupon)
-        instance._thisptr = static_pointer_cast[CashFlow](
-            (<_cfc.CappedFlooredCoupon*>self._thisptr.get()).underlying())
+        instance._thisptr = self.as_ptr().underlying()
         return instance
 
+def as_capped_floored_coupon(CashFlow cf):
+    cdef CappedFlooredCoupon coupon = CappedFlooredCoupon.__new__(CappedFlooredCoupon)
+    coupon._thisptr = dynamic_pointer_cast[_cfc.CappedFlooredCoupon](cf._thisptr)
+    if not coupon._thisptr:
+        return None
+    else:
+        return coupon
+
 cdef class CappedFlooredIborCoupon(CappedFlooredCoupon):
     def __init__(self, Date payment_date not None,
                  Real nominal,
@@ -80,7 +90,8 @@ cdef class CappedFlooredIborCoupon(CappedFlooredCoupon):
                  Date ref_period_end=Date(),
                  DayCounter day_counter=DayCounter(),
                  bool is_in_arrears=False):
-        self._thisptr = shared_ptr[CashFlow](new _cfc.CappedFlooredIborCoupon(
+        self._thisptr.reset(
+            new _cfc.CappedFlooredIborCoupon(
                 payment_date._thisptr,
                 nominal,
                 start_date._thisptr,
@@ -94,7 +105,8 @@ cdef class CappedFlooredIborCoupon(CappedFlooredCoupon):
                 ref_period_start._thisptr,
                 ref_period_end._thisptr,
                 deref(day_counter._thisptr),
-                is_in_arrears))
+                is_in_arrears)
+        )
 
 cdef class CappedFlooredCmsCoupon(CappedFlooredCoupon):
     def __init__(self, Date payment_date not None,
@@ -111,7 +123,8 @@ cdef class CappedFlooredCmsCoupon(CappedFlooredCoupon):
                  Date ref_period_end=Date(),
                  DayCounter day_counter=DayCounter(),
                  bool is_in_arrears=False):
-        self._thisptr = shared_ptr[CashFlow](new _cfc.CappedFlooredCmsCoupon(
+        self._thisptr.reset(
+            new _cfc.CappedFlooredCmsCoupon(
                 payment_date._thisptr,
                 nominal,
                 start_date._thisptr,
@@ -125,4 +138,6 @@ cdef class CappedFlooredCmsCoupon(CappedFlooredCoupon):
                 ref_period_start._thisptr,
                 ref_period_end._thisptr,
                 deref(day_counter._thisptr),
-                is_in_arrears))
+                is_in_arrears
+            )
+        )
diff --git a/quantlib/cashflows/cashflows.pyx b/quantlib/cashflows/cashflows.pyx
index f66680132..bd5bea6ed 100644
--- a/quantlib/cashflows/cashflows.pyx
+++ b/quantlib/cashflows/cashflows.pyx
@@ -1,37 +1,105 @@
 from cython.operator cimport dereference as deref
 from libcpp cimport bool
+from quantlib.ext cimport optional, nullopt
 from quantlib.termstructures.yield_term_structure cimport YieldTermStructure
-from quantlib.time.date cimport Date
+from quantlib.time.date cimport Date, _pydate_from_qldate
+from quantlib.time._date cimport Date as QlDate
 from ..cashflow cimport Leg
 from ._cashflows cimport CashFlows
 
-def previous_cash_flow_amount(Leg leg, bool include_settlement_date_flows, Date settlement_date=Date()):
-    return CashFlows.previousCashFlowAmount(leg._thisptr, include_settlement_date_flows, settlement_date._thisptr)
+def previous_cash_flow_amount(Leg leg, include_settlement_date_flows=None, Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    return CashFlows.previousCashFlowAmount(leg._thisptr, include_settlement_date_flows_opt, settlement_date._thisptr)
 
-def next_cash_flow_amount(Leg leg, bool include_settlement_date_flows, Date settlement_date=Date()):
-    return CashFlows.nextCashFlowAmount(leg._thisptr, include_settlement_date_flows, settlement_date._thisptr)
+def next_cash_flow_amount(Leg leg, include_settlement_date_flows=None, Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    return CashFlows.nextCashFlowAmount(leg._thisptr, include_settlement_date_flows_opt, settlement_date._thisptr)
 
 
-def npv(Leg leg, YieldTermStructure discount_curve, bool include_settlement_date_flows,
+def npv(Leg leg, YieldTermStructure discount_curve, include_settlement_date_flows=None,
         Date settlement_date=Date(), Date npv_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+
     return CashFlows.npv(leg._thisptr,
                          deref(discount_curve.as_yts_ptr()),
-                         include_settlement_date_flows,
+                         include_settlement_date_flows_opt,
                          settlement_date._thisptr,
                          npv_date._thisptr)
 
-def bps(Leg leg, YieldTermStructure discount_curve, bool include_settlement_date_flows,
+def bps(Leg leg, YieldTermStructure discount_curve, include_settlement_date_flows=None,
         Date settlement_date=Date(), Date npv_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
     return CashFlows.bps(leg._thisptr,
                          deref(discount_curve.as_yts_ptr()),
-                         include_settlement_date_flows,
+                         include_settlement_date_flows_opt,
                          settlement_date._thisptr,
                          npv_date._thisptr)
 
-def npvbps(Leg leg, YieldTermStructure discount_curve, bool include_settlement_date_flows,
+def npvbps(Leg leg, YieldTermStructure discount_curve, include_settlement_date_flows=None,
         Date settlement_date=Date(), Date npv_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
     return CashFlows.npvbps(leg._thisptr,
                             deref(discount_curve.as_yts_ptr()),
-                            include_settlement_date_flows,
+                            include_settlement_date_flows_opt,
                             settlement_date._thisptr,
                             npv_date._thisptr)
+
+
+def accrual_start_date(Leg leg, include_settlement_date_flows=None,
+                       Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    cdef QlDate d
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    d = CashFlows.accrualStartDate(leg._thisptr,
+                                   include_settlement_date_flows_opt,
+                                   settlement_date._thisptr)
+    return _pydate_from_qldate(d)
+
+def accrual_end_date(Leg leg, include_settlement_date_flows=None,
+                     Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    d = CashFlows.accrualEndDate(leg._thisptr,
+                                 include_settlement_date_flows_opt,
+                                 settlement_date._thisptr)
+    return _pydate_from_qldate(d)
+
+
+def accrual_days(Leg leg, include_settlement_date_flows=None,
+                 Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    return CashFlows.accrualDays(leg._thisptr,
+                                 include_settlement_date_flows_opt,
+                                 settlement_date._thisptr)
+
+def accrued_days(Leg leg, include_settlement_date_flows=None,
+                 Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    return CashFlows.accruedDays(leg._thisptr,
+                                 include_settlement_date_flows_opt,
+                                 settlement_date._thisptr)
+
+def accrued_amount(Leg leg, include_settlement_date_flows=None,
+                   Date settlement_date=Date()):
+    cdef optional[bool] include_settlement_date_flows_opt = nullopt
+    if include_settlement_date_flows is not None:
+        include_settlement_date_flows_opt = <bool>include_settlement_date_flows
+    return CashFlows.accruedAmount(leg._thisptr,
+                                   include_settlement_date_flows_opt,
+                                   settlement_date._thisptr)
diff --git a/quantlib/cashflows/coupon.pxd b/quantlib/cashflows/coupon.pxd
index 76c502f7a..310f1829c 100644
--- a/quantlib/cashflows/coupon.pxd
+++ b/quantlib/cashflows/coupon.pxd
@@ -2,4 +2,4 @@ from quantlib.cashflow cimport CashFlow
 cimport quantlib.cashflows._coupon as _coupon
 
 cdef class Coupon(CashFlow):
-    cdef inline _coupon.Coupon* _get_coupon(self)
+    cdef inline _coupon.Coupon* _get_coupon(self) noexcept
diff --git a/quantlib/cashflows/coupon.pyx b/quantlib/cashflows/coupon.pyx
index 7b53e7601..1c2830bfb 100644
--- a/quantlib/cashflows/coupon.pyx
+++ b/quantlib/cashflows/coupon.pyx
@@ -8,7 +8,7 @@ cimport quantlib._cashflow as _cf
 
 cdef class Coupon(CashFlow):
 
-    cdef inline _coupon.Coupon* _get_coupon(self):
+    cdef inline _coupon.Coupon* _get_coupon(self) noexcept:
         return <_coupon.Coupon*>self._thisptr.get()
 
     @property
@@ -61,3 +61,8 @@ cdef class Coupon(CashFlow):
         cdef DayCounter dc = DayCounter.__new__(DayCounter)
         dc._thisptr = new _dc.DayCounter(self._get_coupon().dayCounter())
         return dc
+
+def as_coupon(CashFlow cf):
+    cdef Coupon coupon = Coupon.__new__(Coupon)
+    coupon._thisptr = cf._thisptr
+    return coupon
diff --git a/quantlib/cashflows/fixed_rate_coupon.pyx b/quantlib/cashflows/fixed_rate_coupon.pyx
index 47639fc57..d38e39091 100644
--- a/quantlib/cashflows/fixed_rate_coupon.pyx
+++ b/quantlib/cashflows/fixed_rate_coupon.pyx
@@ -3,7 +3,7 @@ from cython.operator cimport dereference as deref, preincrement as preinc
 from libcpp.vector cimport vector
 from libcpp.utility cimport move
 from quantlib.compounding cimport Compounding
-from quantlib.ext cimport shared_ptr
+from quantlib.ext cimport shared_ptr, dynamic_pointer_cast
 from quantlib.time.businessdayconvention cimport BusinessDayConvention
 from quantlib.time.calendar cimport Calendar
 from quantlib.time.date cimport Date
@@ -12,6 +12,7 @@ from quantlib.time.daycounter cimport DayCounter
 from quantlib.time.schedule cimport Schedule
 cimport quantlib._cashflow as _cf
 from quantlib.interest_rate cimport InterestRate
+from ..cashflow cimport CashFlow
 from .._cashflow cimport Leg as QlLeg
 cimport quantlib._interest_rate as _ir
 
@@ -36,6 +37,15 @@ cdef class FixedRateCoupon(Coupon):
         ir._thisptr = (<_frc.FixedRateCoupon*>self._thisptr.get()).interestRate()
         return ir
 
+def as_fixed_rate_coupon(CashFlow cf):
+    cdef FixedRateCoupon coupon = FixedRateCoupon.__new__(FixedRateCoupon)
+    coupon._thisptr = dynamic_pointer_cast[_frc.FixedRateCoupon](cf._thisptr)
+    if not coupon._thisptr:
+        return None
+    else:
+        return coupon
+
+
 cdef class FixedRateLeg(Leg):
 
     def __init__(self, Schedule schedule):
diff --git a/quantlib/cashflows/floating_rate_coupon.pxd b/quantlib/cashflows/floating_rate_coupon.pxd
index dcc085f9f..e47a9b973 100644
--- a/quantlib/cashflows/floating_rate_coupon.pxd
+++ b/quantlib/cashflows/floating_rate_coupon.pxd
@@ -2,4 +2,4 @@ from quantlib.cashflows.coupon cimport Coupon
 from . cimport _floating_rate_coupon as _frc
 
 cdef class FloatingRateCoupon(Coupon):
-    cdef inline _frc.FloatingRateCoupon* _get_frc(self)
+    cdef inline _frc.FloatingRateCoupon* _get_frc(self) noexcept
diff --git a/quantlib/cashflows/floating_rate_coupon.pyx b/quantlib/cashflows/floating_rate_coupon.pyx
index 9ec4a397f..497389074 100644
--- a/quantlib/cashflows/floating_rate_coupon.pyx
+++ b/quantlib/cashflows/floating_rate_coupon.pyx
@@ -1,11 +1,13 @@
 from quantlib.types cimport Natural, Real, Spread
 from libcpp cimport bool
 from cython.operator cimport dereference as deref
-from quantlib.ext cimport shared_ptr, static_pointer_cast
+from quantlib.ext cimport shared_ptr, static_pointer_cast, dynamic_pointer_cast
+from quantlib.handle cimport HandleYieldTermStructure
 from quantlib.time.date cimport Date, date_from_qldate
 from quantlib.time.daycounter cimport DayCounter
 from .coupon_pricer cimport FloatingRateCouponPricer
 cimport quantlib._cashflow as _cf
+from ..cashflow cimport CashFlow
 from quantlib.indexes.interest_rate_index cimport InterestRateIndex
 cimport quantlib.indexes._interest_rate_index as _iri
 from quantlib._index cimport Index
@@ -28,7 +30,7 @@ cdef class FloatingRateCoupon(Coupon):
                 deref(day_counter._thisptr), is_in_arrears)
         )
 
-    cdef inline _frc.FloatingRateCoupon* _get_frc(self):
+    cdef inline _frc.FloatingRateCoupon* _get_frc(self) noexcept:
         return <_frc.FloatingRateCoupon*>self._thisptr.get()
 
     def set_pricer(self, FloatingRateCouponPricer pricer not None):
@@ -38,6 +40,14 @@ cdef class FloatingRateCoupon(Coupon):
     def fixing_days(self):
         return self._get_frc().fixingDays()
 
+    @property
+    def gearing(self):
+        return self._get_frc().gearing()
+
+    @property
+    def spread(self):
+        return self._get_frc().spread()
+
     @property
     def fixing_date(self):
         return date_from_qldate(self._get_frc().fixingDate())
@@ -63,3 +73,14 @@ cdef class FloatingRateCoupon(Coupon):
     @property
     def is_in_arrears(self):
         return self._get_frc().isInArrears()
+
+    def price(self, HandleYieldTermStructure discountingCurve):
+        return self._get_frc().price(discountingCurve.handle())
+
+def as_floating_rate_coupon(CashFlow cf):
+    cdef FloatingRateCoupon coupon = FloatingRateCoupon.__new__(FloatingRateCoupon)
+    coupon._thisptr = dynamic_pointer_cast[_frc.FloatingRateCoupon](cf._thisptr)
+    if not coupon._thisptr:
+        return None
+    else:
+        return coupon
diff --git a/quantlib/cashflows/ibor_coupon.pyx b/quantlib/cashflows/ibor_coupon.pyx
index c242c565c..43bc454a0 100644
--- a/quantlib/cashflows/ibor_coupon.pyx
+++ b/quantlib/cashflows/ibor_coupon.pyx
@@ -2,11 +2,12 @@ include '../types.pxi'
 
 from libcpp cimport bool
 from cython.operator cimport dereference as deref
-from quantlib.ext cimport shared_ptr, static_pointer_cast
+from quantlib.ext cimport shared_ptr, static_pointer_cast, dynamic_pointer_cast
 from quantlib.time.date cimport Date
 from quantlib.time.daycounter cimport DayCounter
 cimport quantlib.cashflows._ibor_coupon as _ic
-cimport quantlib._cashflow as _cf
+from ..cashflow cimport CashFlow
+from .. cimport _cashflow as _cf
 cimport quantlib.indexes._ibor_index as _ii
 from quantlib.indexes.ibor_index cimport IborIndex
 
@@ -18,7 +19,7 @@ cdef class IborCoupon(FloatingRateCoupon):
                  Spread spread=0.,
                  Date ref_period_start=Date(), Date ref_period_end=Date(),
                  DayCounter day_counter=DayCounter(), bool is_in_arrears=False):
-        self._thisptr = shared_ptr[_cf.CashFlow](
+        self._thisptr.reset(
             new _ic.IborCoupon(
                 payment_date._thisptr, nominal,
                 start_date._thisptr, end_date._thisptr,
@@ -26,10 +27,19 @@ cdef class IborCoupon(FloatingRateCoupon):
                 static_pointer_cast[_ii.IborIndex](index._thisptr),
                 gearing, spread,
                 ref_period_start._thisptr, ref_period_end._thisptr,
-                deref(day_counter._thisptr), is_in_arrears)
+                deref(day_counter._thisptr), is_in_arrears
+            )
         )
     Settings = IborCouponSettings()
 
+def as_ibor_coupon(CashFlow cf):
+    cdef IborCoupon coupon = IborCoupon.__new__(IborCoupon)
+    coupon._thisptr = dynamic_pointer_cast[_ic.IborCoupon](cf._thisptr)
+    if not coupon._thisptr:
+        return None
+    else:
+        return coupon
+
 cdef class IborCouponSettings:
     @staticmethod
     def create_at_par_coupons():
diff --git a/quantlib/cashflows/overnight_indexed_coupon.pyx b/quantlib/cashflows/overnight_indexed_coupon.pyx
index 27ced848e..2f5fed1bc 100644
--- a/quantlib/cashflows/overnight_indexed_coupon.pyx
+++ b/quantlib/cashflows/overnight_indexed_coupon.pyx
@@ -1,10 +1,10 @@
-from quantlib.types cimport Integer, Natural, Real, Spread
+from quantlib.types cimport Integer, Natural, Rate, Real, Spread
 
 from libcpp cimport bool
 from libcpp.vector cimport vector
 from libcpp.utility cimport move
 from cython.operator cimport dereference as deref, preincrement as preinc
-from quantlib.ext cimport make_shared, shared_ptr, static_pointer_cast
+from quantlib.ext cimport make_shared, shared_ptr, static_pointer_cast, dynamic_pointer_cast
 from quantlib.time.businessdayconvention cimport BusinessDayConvention
 from quantlib.time.date cimport Date, date_from_qldate
 from quantlib.time._date cimport Date as QlDate
@@ -16,8 +16,10 @@ from quantlib.utilities.null cimport Null
 cimport quantlib.indexes._ibor_index as _ii
 cimport quantlib._cashflow as _cf
 from .rateaveraging cimport RateAveraging
+from .overnight_indexed_coupon_pricer cimport OvernightIndexedCouponPricer
 from . cimport _overnight_indexed_coupon as _oic
 from .._cashflow cimport Leg as QlLeg
+from ..cashflow cimport CashFlow
 
 cdef class OvernightIndexedCoupon(FloatingRateCoupon):
 
@@ -84,6 +86,19 @@ cdef class OvernightIndexedCoupon(FloatingRateCoupon):
     def apply_observation_shift(self):
         return (<_oic.OvernightIndexedCoupon*>self._thisptr.get()).applyObservationShift()
 
+    @property
+    def compound_spread_daily(self):
+        return (<_oic.OvernightIndexedCoupon*>self._thisptr.get()).compoundSpreadDaily()
+
+def as_overnight_indexed_coupon(CashFlow cf):
+    cdef OvernightIndexedCoupon coupon = OvernightIndexedCoupon.__new__(OvernightIndexedCoupon)
+    coupon._thisptr = dynamic_pointer_cast[_oic.OvernightIndexedCoupon](cf._thisptr)
+    if not coupon._thisptr:
+        return None
+    else:
+        return coupon
+
+
 cdef class OvernightLeg(Leg):
 
     def __iter__(self):
@@ -124,6 +139,10 @@ cdef class OvernightLeg(Leg):
         self.leg.withSpreads(spread)
         return self
 
+    def with_averaging_method(self, RateAveraging averaging_method):
+        self.leg.withAveragingMethod(averaging_method)
+        return self
+
     def with_observation_shift(self, bool apply_observation_shift=True):
         self.leg.withObservationShift(apply_observation_shift)
         return self
@@ -140,6 +159,34 @@ cdef class OvernightLeg(Leg):
         self.leg.withPaymentLag(lag)
         return self
 
+    def compounding_spread_daily(self, bool compound_spread_daily=True):
+        self.leg.compoundingSpreadDaily(compound_spread_daily)
+        return self
+
+    def with_caps(self, caps):
+        cdef vector[Rate] c_caps
+        if isinstance(caps, list):
+            c_caps = <list>caps
+            self.leg.withCaps(c_caps)
+        else:
+            self.leg.withCaps(<Rate>caps)
+        return self
+
+    def with_floors(self, floors):
+        cdef vector[Rate] c_floors
+        if isinstance(floors, list):
+            c_floors = <list>floors
+            self.leg.withFloors(c_floors)
+        else:
+            self.leg.withFloors(<Rate>floors)
+        return self
+
+    def with_coupon_pricer(self, OvernightIndexedCouponPricer coupon_pricer):
+        self.leg.withCouponPricer(
+            static_pointer_cast[_oic.OvernightIndexedCouponPricer](coupon_pricer._thisptr)
+        )
+        return self
+
     def __call__(self):
         self._thisptr = move[QlLeg](_oic.to_leg(deref(self.leg)))
         return self
diff --git a/quantlib/cashflows/overnight_indexed_coupon_pricer.pxd b/quantlib/cashflows/overnight_indexed_coupon_pricer.pxd
index 42e14a891..431049f81 100644
--- a/quantlib/cashflows/overnight_indexed_coupon_pricer.pxd
+++ b/quantlib/cashflows/overnight_indexed_coupon_pricer.pxd
@@ -1,8 +1,11 @@
 from .coupon_pricer cimport FloatingRateCouponPricer
 
-cdef class CompoundingOvernightIndexedCouponPricer(FloatingRateCouponPricer):
+cdef class OvernightIndexedCouponPricer(FloatingRateCouponPricer):
+    pass
+
+cdef class CompoundingOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
      pass
 
 
-cdef class ArithmeticAveragedOvernightIndexedCouponPricer(FloatingRateCouponPricer):
+cdef class ArithmeticAveragedOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
     pass
diff --git a/quantlib/cashflows/overnight_indexed_coupon_pricer.pyx b/quantlib/cashflows/overnight_indexed_coupon_pricer.pyx
index e359b9996..2ea198d42 100644
--- a/quantlib/cashflows/overnight_indexed_coupon_pricer.pyx
+++ b/quantlib/cashflows/overnight_indexed_coupon_pricer.pyx
@@ -1,16 +1,26 @@
 from quantlib.types cimport Real
 from libcpp cimport bool
+from quantlib.handle cimport Handle, HandleOptionletVolatilityStructure
 from . cimport _overnight_indexed_coupon_pricer as _oicp
 
-cdef class CompoundingOvernightIndexedCouponPricer(FloatingRateCouponPricer):
+
+cdef class CompoundingOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
      def __init__(self):
          self._thisptr.reset(new _oicp.CompoundingOvernightIndexedCouponPricer())
 
-cdef class ArithmeticAveragedOvernightIndexedCouponPricer(FloatingRateCouponPricer):
-    def __init__(self, Real mean_reversion = 0.03, Real volatility=0.0, bool by_approx=False):
+cdef class ArithmeticAveragedOvernightIndexedCouponPricer(OvernightIndexedCouponPricer):
+    def __init__(self, Real mean_reversion = 0.03, Real volatility=0.0, bool by_approx=False, HandleOptionletVolatilityStructure v = HandleOptionletVolatilityStructure(), bool effective_volatility_input = False):
         """ pricer for arithmetically averaged overnight indexed coupons
 
         Reference: Katsumi Takada 2011, Valuation of Arithmetically Average of
         Fed Funds Rates and Construction of the US Dollar Swap Yield Curve"""
 
-        self._thisptr.reset(new _oicp.ArithmeticAveragedOvernightIndexedCouponPricer(mean_reversion, volatility, by_approx))
+        self._thisptr.reset(
+            new _oicp.ArithmeticAveragedOvernightIndexedCouponPricer(
+                mean_reversion,
+                volatility,
+                by_approx,
+                v.handle(),
+                effective_volatility_input
+            )
+        )
diff --git a/quantlib/ext.pxd b/quantlib/ext.pxd
index 5de844ed7..4b52acce8 100644
--- a/quantlib/ext.pxd
+++ b/quantlib/ext.pxd
@@ -27,9 +27,10 @@ cdef extern from 'ql/optional.hpp' namespace 'QuantLib::ext' nogil:
         optional()
         optional(nullopt_t)
         optional(const T&) except +
-        T& value()
+        T& value() except +
         T& value_or[U](U& default_value)
         bool operator!()
         optional& operator=(optional&)
+        optional& operator=[U](U&)
 
     optional[T] make_optional[T](...) except +
diff --git a/quantlib/indexes/api.py b/quantlib/indexes/api.py
index 5901a44b0..f4747fad4 100644
--- a/quantlib/indexes/api.py
+++ b/quantlib/indexes/api.py
@@ -10,6 +10,7 @@
 from .ibor.libor import Libor
 from .ibor.euribor import Euribor, Euribor3M, Euribor6M
 from .ibor.eonia import Eonia
+from .ibor.fedfunds import FedFunds
 from .ibor.sofr import Sofr
 from .ibor.usdlibor import USDLibor
 from .ibor_index import IborIndex
diff --git a/quantlib/indexes/ibor/_fedfunds.pxd b/quantlib/indexes/ibor/_fedfunds.pxd
new file mode 100644
index 000000000..6f22fbfc1
--- /dev/null
+++ b/quantlib/indexes/ibor/_fedfunds.pxd
@@ -0,0 +1,8 @@
+from quantlib._handle cimport Handle
+from quantlib.termstructures._yield_term_structure cimport YieldTermStructure
+from quantlib.indexes._ibor_index cimport OvernightIndex
+
+cdef extern from 'ql/indexes/ibor/fedfunds.hpp' namespace 'QuantLib' nogil:
+
+    cdef cppclass FedFunds(OvernightIndex):
+        FedFunds(Handle[YieldTermStructure]& h) except +
diff --git a/quantlib/indexes/ibor/_sofr.pxd b/quantlib/indexes/ibor/_sofr.pxd
index f6381db0c..7e5de49ae 100644
--- a/quantlib/indexes/ibor/_sofr.pxd
+++ b/quantlib/indexes/ibor/_sofr.pxd
@@ -2,7 +2,7 @@ from quantlib._handle cimport Handle
 from quantlib.termstructures._yield_term_structure cimport YieldTermStructure
 from quantlib.indexes._ibor_index cimport OvernightIndex
 
-cdef extern from 'ql/indexes/ibor/sofr.hpp' namespace 'QuantLib':
+cdef extern from 'ql/indexes/ibor/sofr.hpp' namespace 'QuantLib' nogil:
 
     cdef cppclass Sofr(OvernightIndex):
         Sofr(Handle[YieldTermStructure]& h) except +
diff --git a/quantlib/indexes/ibor/fedfunds.pxd b/quantlib/indexes/ibor/fedfunds.pxd
new file mode 100644
index 000000000..65356410e
--- /dev/null
+++ b/quantlib/indexes/ibor/fedfunds.pxd
@@ -0,0 +1,4 @@
+from ..ibor_index cimport OvernightIndex
+
+cdef class FedFunds(OvernightIndex):
+    pass
diff --git a/quantlib/indexes/ibor/fedfunds.pyx b/quantlib/indexes/ibor/fedfunds.pyx
new file mode 100644
index 000000000..009e84d76
--- /dev/null
+++ b/quantlib/indexes/ibor/fedfunds.pyx
@@ -0,0 +1,7 @@
+from quantlib.handle cimport HandleYieldTermStructure
+from . cimport _fedfunds as _ff
+from ... cimport _index as _in
+
+cdef class FedFunds(OvernightIndex):
+    def __init__(self, HandleYieldTermStructure yts=HandleYieldTermStructure()):
+        self._thisptr.reset(new _ff.FedFunds(yts.handle()))
diff --git a/quantlib/methods/montecarlo/_pathgenerator.pxd b/quantlib/methods/montecarlo/_pathgenerator.pxd
new file mode 100644
index 000000000..d749d3ec2
--- /dev/null
+++ b/quantlib/methods/montecarlo/_pathgenerator.pxd
@@ -0,0 +1,17 @@
+from libcpp cimport bool
+from quantlib._time_grid cimport TimeGrid
+from libcpp.vector cimport vector
+from ._multipath cimport Path
+from ._sample cimport Sample
+from quantlib._stochastic_process cimport StochasticProcess
+
+cdef extern from 'ql/methods/montecarlo/pathgenerator.hpp' namespace 'QuantLib' nogil:
+    cdef cppclass PathGenerator[GSG]:
+        ctypedef Sample[Path] sample_type
+        MultiPathGenerator(const shared_ptr[StochasticProcess]&,
+                           const TimeGrid&,
+                           GSG generator,
+                           bool brownianBridge) # = false)
+        const sample_type& next()
+        const sample_type& antithetic()
+        Size size()
diff --git a/quantlib/models/shortrate/_twofactor_model.pxd b/quantlib/models/shortrate/_twofactor_model.pxd
index b69638b75..720b99307 100644
--- a/quantlib/models/shortrate/_twofactor_model.pxd
+++ b/quantlib/models/shortrate/_twofactor_model.pxd
@@ -2,7 +2,7 @@ from quantlib.types cimport DiscountFactor, Rate, Real, Time
 from quantlib.math._array cimport Array
 from quantlib.models._model cimport ShortRateModel, AffineModel
 from quantlib.ext cimport shared_ptr
-from quantlib._stochastic_process cimport StochasticProcess1D
+from quantlib._stochastic_process cimport StochasticProcess, StochasticProcess1D
 
 cdef extern from 'ql/models/shortrate/twofactormodel.hpp' namespace 'QuantLib' nogil:
 
@@ -11,7 +11,9 @@ cdef extern from 'ql/models/shortrate/twofactormodel.hpp' namespace 'QuantLib' n
             ShortRateDynamics(shared_ptr[StochasticProcess1D]& xProcess,
                               shared_ptr[StochasticProcess1D]& yProcess,
                               Real correlation)
+            Real correlation()
             Rate shortRate(Time t, Real x, Real y)
             shared_ptr[StochasticProcess1D]& xProcess()
             shared_ptr[StochasticProcess1D]& yProcess()
+            shared_ptr[StochasticProcess]& process()
         shared_ptr[ShortRateDynamics] dynamics()
diff --git a/quantlib/models/shortrate/twofactor_model.pyx b/quantlib/models/shortrate/twofactor_model.pyx
index fe874e64f..027b7277c 100644
--- a/quantlib/models/shortrate/twofactor_model.pyx
+++ b/quantlib/models/shortrate/twofactor_model.pyx
@@ -22,6 +22,11 @@ cdef class ShortRateDynamics:
     def short_rate(self, Time t, Real x, Real y):
         return self._thisptr.get().shortRate(t, x, y)
 
+    @property
+    def correlation(self):
+        """Correlation :math:`rho` between the two brownian motions"""
+        return self._thisptr.get().correlation()
+
 cdef class TwoFactorModel(ShortRateModel):
 
     @property
diff --git a/quantlib/pricingengines/bond/_riskybondengine.pxd b/quantlib/pricingengines/bond/_riskybondengine.pxd
new file mode 100644
index 000000000..4060636ca
--- /dev/null
+++ b/quantlib/pricingengines/bond/_riskybondengine.pxd
@@ -0,0 +1,5 @@
+from .._pricing_engine cimport PricingEngine
+
+cdef extrn from 'ql/pricingengines/bond/riskybondengine.hpp' namespace 'QuantLib' nogil:
+    cdef cppclass RiskyBondEngine(PricingEngine):
+        pass
diff --git a/quantlib/termstructure.pyx b/quantlib/termstructure.pyx
index 9850fcdd9..66362a4a7 100644
--- a/quantlib/termstructure.pyx
+++ b/quantlib/termstructure.pyx
@@ -2,6 +2,7 @@ from quantlib.ext cimport static_pointer_cast
 from quantlib.time.date cimport Date, date_from_qldate
 from quantlib.time._date cimport Date as QlDate
 from quantlib.time.daycounter cimport DayCounter
+from quantlib.time.calendar cimport Calendar
 cimport quantlib.time._daycounter as _dc
 
 cdef class TermStructure(Observable):
@@ -18,20 +19,24 @@ cdef class TermStructure(Observable):
         return static_pointer_cast[QlObservable](self._thisptr)
 
     def time_from_reference(self, Date dt):
+        """date/time conversion"""
         return self.as_ptr().timeFromReference(dt._thisptr)
 
     @property
     def reference_date(self):
+        """ the date at which discount = 1.0 and/or variance = 0.0"""
         cdef QlDate ref_date = self.as_ptr().referenceDate()
         return date_from_qldate(ref_date)
 
     @property
     def max_date(self):
+        """the latest date for which the curve can return values"""
         cdef QlDate max_date = self.as_ptr().maxDate()
         return date_from_qldate(max_date)
 
     @property
     def max_time(self):
+        """the latest time for which the curve can return values"""
         return self.as_ptr().maxTime()
 
     @property
@@ -42,4 +47,11 @@ cdef class TermStructure(Observable):
 
     @property
     def settlement_days(self):
+        """ number of settlement days used for reference date calculation"""
         return self.as_ptr().settlementDays()
+
+    @property
+    def calendar(self):
+        cdef Calendar instance = Calendar.__new__(Calendar)
+        instance._thisptr = self.as_ptr().calendar()
+        return instance
diff --git a/quantlib/termstructures/_inflation_term_structure.pxd b/quantlib/termstructures/_inflation_term_structure.pxd
index 45d982137..638ed3390 100644
--- a/quantlib/termstructures/_inflation_term_structure.pxd
+++ b/quantlib/termstructures/_inflation_term_structure.pxd
@@ -12,52 +12,36 @@ include '../types.pxi'
 from libcpp cimport bool
 
 from quantlib.ext cimport shared_ptr
-from quantlib.handle cimport Handle
 from quantlib.time._date cimport Date
 from quantlib.time._calendar cimport Calendar
 from quantlib.time._daycounter cimport DayCounter
 from quantlib.time._period cimport Period, Frequency
-from quantlib.termstructures._yield_term_structure cimport YieldTermStructure
 from quantlib.termstructures.inflation._seasonality cimport Seasonality
-
+from .._termstructure cimport TermStructure
 
 cdef extern from 'ql/termstructures/inflationtermstructure.hpp' namespace 'QuantLib' nogil:
 
-    cdef cppclass InflationTermStructure:
-
-        InflationTermStructure() except +
-        Date& referenceDate()
-        Date& maxDate()
-        Date& baseDate()
-        Rate baseRate()
-
+    cdef cppclass InflationTermStructure(TermStructure):
+        Date baseDate()
+        Real baseRate()
 
     cdef cppclass ZeroInflationTermStructure(InflationTermStructure):
-
-        ZeroInflationTermStructure() except +
-        ZeroInflationTermStructure(DayCounter& dayCounter,
-                                   Rate baseZeroRate,
-                                   Period& lag,
+        ZeroInflationTermStructure(Date baseDate,
                                    Frequency frequency,
-                                   const Handle[YieldTermStructure]& yTS,
+                                   DayCounter& dayCounter,
                                    const shared_ptr[Seasonality]& seasonality # = shared_ptr<Seasonality>()
         ) except +
         ZeroInflationTermStructure(const Date& referenceDate,
-                                   const Calendar& calendar,
-                                   const DayCounter& dayCounter,
-                                   Rate baseZeroRate,
-                                   const Period& lag,
+                                   Date baseDate,
                                    Frequency frequency,
-                                   const Handle[YieldTermStructure]& yTS,
+                                   const DayCounter& dayCounter,
                                    const shared_ptr[Seasonality] &seasonality # = shared_ptr<Seasonality>())
         ) except +
         ZeroInflationTermStructure(Natural settlementDays,
                                    const Calendar& calendar,
-                                   const DayCounter& dayCounter,
-                                   Rate baseZeroRate,
-                                   const Period& lag,
+                                   Date baseDate,
                                    Frequency frequency,
-                                   const Handle[YieldTermStructure]& yTS,
+                                   const DayCounter& dayCounter,
                                    const shared_ptr[Seasonality] &seasonality # = boost::shared_ptr<Seasonality>()
         ) except +
 
@@ -71,15 +55,23 @@ cdef extern from 'ql/termstructures/inflationtermstructure.hpp' namespace 'Quant
 
 
     cdef cppclass YoYInflationTermStructure(InflationTermStructure):
-
-        YoYInflationTermStructure() except +
-
         YoYInflationTermStructure(DayCounter& dayCounter,
-                                  Rate baseZeroRate,
-                                  Period& lag,
+                                  Rate baseYoYRate,
+                                  Frequency frequency,
+                                  const DayCounter& dayCounter,
+                                  const shared_ptr[Seasonality]& seasonality) except +
+        YoYInflationTermStructure(Date& referenceDate,
+                                  Date baseDate,
+                                  Rate baseYoYRate,
+                                  Frequency frequency,
+                                  const DayCounter& dayCounter,
+                                  const shared_ptr[Seasonality]& seasonality) except +
+        YoYInflationTermStructure(Natural settlmentDays,
+                                  const Calendar& calendar,
+                                  Date baseDate,
+                                  Rate baseYoYRate,
                                   Frequency frequency,
-                                  bool indexIsInterpolated,
-                                  const Handle[YieldTermStructure]& yTS,
+                                  const DayCounter& dayCounter,
                                   const shared_ptr[Seasonality]& seasonality) except +
 
         Rate yoyRate(Date& d,
diff --git a/quantlib/termstructures/_vol_term_structure.pxd b/quantlib/termstructures/_vol_term_structure.pxd
index e49da1fb9..5cf12ba0f 100644
--- a/quantlib/termstructures/_vol_term_structure.pxd
+++ b/quantlib/termstructures/_vol_term_structure.pxd
@@ -5,9 +5,10 @@ from quantlib.time._calendar cimport Calendar
 from quantlib.time._date cimport Date
 from quantlib.time._period cimport Period
 from quantlib.time.businessdayconvention cimport BusinessDayConvention
+from .._termstructure cimport TermStructure
 
 cdef extern from 'ql/termstructures/voltermstructure.hpp' namespace 'QuantLib' nogil:
-    cdef cppclass VolatilityTermStructure:
+    cdef cppclass VolatilityTermStructure(TermStructure):
         VolatilityTermStructure(BusinessDayConvention bdc,
                                 const DayCounter& dc) # = DayCounter()
         #initialize with a fixed reference date
diff --git a/quantlib/termstructures/inflation/seasonality.pyx b/quantlib/termstructures/inflation/seasonality.pyx
index 8dddf7e53..f856ce219 100644
--- a/quantlib/termstructures/inflation/seasonality.pyx
+++ b/quantlib/termstructures/inflation/seasonality.pyx
@@ -35,7 +35,8 @@ cdef class Seasonality:
         return self._thisptr.get().correctZeroRate(
             d._thisptr,
             r,
-            deref(iTS._thisptr))
+            deref(<_if.InflationTermStructure*>iTS._thisptr.get())
+        )
 
     def correctYoYRate(self,
 		    Date d,
@@ -45,13 +46,14 @@ cdef class Seasonality:
         return self._thisptr.get().correctYoYRate(
             d._thisptr,
             r,
-            deref(iTS._thisptr))
+            deref(<_if.InflationTermStructure*>iTS._thisptr.get()))
 
     def isConsistent(self,
 		    InflationTermStructure iTS):
 
         return self._thisptr.get().isConsistent(
-            deref(iTS._thisptr))
+        deref(<_if.InflationTermStructure*>iTS._thisptr.get())
+        )
 
 
 cdef class MultiplicativePriceSeasonality(Seasonality):
@@ -92,4 +94,5 @@ cdef class MultiplicativePriceSeasonality(Seasonality):
     def isConsistent(self, InflationTermStructure iTS):
 
         return self._thisptr.get().isConsistent(
-            deref(iTS._thisptr))
+            deref(<_if.InflationTermStructure*>iTS._thisptr.get())
+        )
diff --git a/quantlib/termstructures/inflation_term_structure.pxd b/quantlib/termstructures/inflation_term_structure.pxd
index 02b985677..024b9e94f 100644
--- a/quantlib/termstructures/inflation_term_structure.pxd
+++ b/quantlib/termstructures/inflation_term_structure.pxd
@@ -1,8 +1,7 @@
-cimport quantlib.termstructures._inflation_term_structure as _its
-from quantlib.ext cimport shared_ptr
+from ..termstructure cimport TermStructure
 
-cdef class InflationTermStructure:
-    cdef shared_ptr[_its.InflationTermStructure] _thisptr
+cdef class InflationTermStructure(TermStructure):
+    pass
 
 cdef class ZeroInflationTermStructure(InflationTermStructure):
     pass
diff --git a/quantlib/termstructures/inflation_term_structure.pyx b/quantlib/termstructures/inflation_term_structure.pyx
index e2d47f9bd..d45af4a33 100644
--- a/quantlib/termstructures/inflation_term_structure.pyx
+++ b/quantlib/termstructures/inflation_term_structure.pyx
@@ -14,45 +14,23 @@ from quantlib.time.date cimport Date, Period, date_from_qldate, period_from_qlpe
 
 from libcpp.vector cimport vector
 from cython.operator cimport dereference as deref
-from quantlib.ext cimport static_pointer_cast
 
-cimport quantlib.time._daycounter as _dc
-from quantlib.time.daycounter cimport DayCounter
+from quantlib.time._period cimport Days
 
-from quantlib.time._period cimport Frequency, Days
-from quantlib.time.calendar cimport Calendar
-
-from quantlib.termstructures.yield_term_structure cimport YieldTermStructure
-
-cimport quantlib.termstructures.yields._flat_forward as _ff
-cimport quantlib._interest_rate as _ir
 cimport quantlib.termstructures._inflation_term_structure as _if
-cimport quantlib.termstructures.inflation._seasonality as _se
-
-from quantlib.termstructures.inflation.seasonality cimport Seasonality
 
-cdef class InflationTermStructure:
+cdef class InflationTermStructure(TermStructure):
     """Abstract Base Class.
     """
 
-    property max_date:
-        def __get__(self):
-            cdef _date.Date max_date = self._thisptr.get().maxDate()
-            return date_from_qldate(max_date)
-
-    @property
-    def reference_date(self):
-        cdef _date.Date reference_date = self._thisptr.get().referenceDate()
-        return date_from_qldate(reference_date)
-
     @property
     def base_date(self):
-        cdef _date.Date base_date = self._thisptr.get().baseDate()
+        cdef _date.Date base_date = (<_if.InflationTermStructure*>self._thisptr.get()).baseDate()
         return date_from_qldate(base_date)
 
     @property
     def base_rate(self):
-        return self._thisptr.get().baseRate()
+        return (<_if.InflationTermStructure*>self._thisptr.get()).baseRate()
 
 cdef class ZeroInflationTermStructure(InflationTermStructure):
 
diff --git a/quantlib/termstructures/vol_term_structure.pxd b/quantlib/termstructures/vol_term_structure.pxd
index 56ab8605c..87124719b 100644
--- a/quantlib/termstructures/vol_term_structure.pxd
+++ b/quantlib/termstructures/vol_term_structure.pxd
@@ -1,7 +1,5 @@
-from libcpp cimport bool as cbool
-from quantlib.ext cimport shared_ptr
+from ..termstructure cimport TermStructure
 from . cimport _vol_term_structure as _vts
 
-cdef class VolatilityTermStructure:
-    cdef shared_ptr[_vts.VolatilityTermStructure] _thisptr
-    cdef _vts.VolatilityTermStructure* as_ptr(self) nogil
+cdef class VolatilityTermStructure(TermStructure):
+    cdef _vts.VolatilityTermStructure* as_vol_ts(self) noexcept nogil
diff --git a/quantlib/termstructures/vol_term_structure.pyx b/quantlib/termstructures/vol_term_structure.pyx
index fdf24a9b8..e7e03c301 100644
--- a/quantlib/termstructures/vol_term_structure.pyx
+++ b/quantlib/termstructures/vol_term_structure.pyx
@@ -1,40 +1,21 @@
 from libcpp cimport bool
 from cython.operator cimport dereference as deref
 from quantlib.time.date cimport date_from_qldate
-from quantlib.time.calendar cimport Calendar
-from quantlib.time.date cimport Date, Period
-cimport quantlib.time._calendar as _calendar
+from quantlib.time.date cimport Period
 
-cdef class VolatilityTermStructure:
+cdef class VolatilityTermStructure(TermStructure):
 
-    cdef inline _vts.VolatilityTermStructure* as_ptr(self) nogil:
-        return self._thisptr.get()
-
-    def time_from_reference(self, Date date not None):
-        return self.as_ptr().timeFromReference(date._thisptr)
-
-    @property
-    def reference_date(self):
-        return date_from_qldate(self.as_ptr().referenceDate())
-
-    @property
-    def calendar(self):
-        cdef Calendar instance = Calendar.__new__(Calendar)
-        instance._thisptr = self.as_ptr().calendar()
-        return instance
-
-    @property
-    def settlement_days(self):
-        return self.as_ptr().settlementDays()
+    cdef inline _vts.VolatilityTermStructure* as_vol_ts(self) noexcept nogil:
+        return <_vts.VolatilityTermStructure*>self._thisptr.get()
 
     def option_date_from_tenor(self, Period period not None):
         return date_from_qldate(
-            self.as_ptr().optionDateFromTenor(deref(period._thisptr)))
+            self.as_vol_ts().optionDateFromTenor(deref(period._thisptr)))
 
     @property
     def extrapolation(self):
-        return self.as_ptr().allowsExtrapolation()
+        return self.as_vol_ts().allowsExtrapolation()
 
     @extrapolation.setter
     def extrapolation(self, bool b):
-        self.as_ptr().enableExtrapolation(b)
+        self.as_vol_ts().enableExtrapolation(b)
diff --git a/quantlib/termstructures/volatility/api.py b/quantlib/termstructures/volatility/api.py
index 9d7ad1526..5ec5656d7 100644
--- a/quantlib/termstructures/volatility/api.py
+++ b/quantlib/termstructures/volatility/api.py
@@ -4,4 +4,6 @@
 from .volatilitytype import VolatilityType
 from .swaption.swaption_vol_matrix import SwaptionVolatilityMatrix
 from .swaption.swaption_constant_vol import ConstantSwaptionVolatility
-from quantlib.handle import HandleSwaptionVolatilityStructure, HandleBlackVolTermStructure, HandleOptionletVolatilityStructure
+from quantlib.handle import (
+    HandleSwaptionVolatilityStructure, HandleBlackVolTermStructure, HandleOptionletVolatilityStructure,
+    RelinkableHandleSwaptionVolatilityStructure, RelinkableHandleBlackVolTermStructure, RelinkableHandleOptionletVolatilityStructure)
diff --git a/quantlib/termstructures/yields/_flat_forward.pxd b/quantlib/termstructures/yields/_flat_forward.pxd
index 049867e7f..28d032af3 100644
--- a/quantlib/termstructures/yields/_flat_forward.pxd
+++ b/quantlib/termstructures/yields/_flat_forward.pxd
@@ -11,7 +11,7 @@ from quantlib.types cimport *
 from libcpp cimport bool
 from libcpp.vector cimport vector
 
-from quantlib.handle cimport Handle
+from quantlib._handle cimport Handle
 from quantlib.time._calendar cimport Calendar
 from quantlib.time._date cimport Date
 from quantlib.time._daycounter cimport DayCounter
diff --git a/quantlib/termstructures/yields/_implied_term_structure.pxd b/quantlib/termstructures/yields/_implied_term_structure.pxd
index e8b3f8c4e..26798a42c 100644
--- a/quantlib/termstructures/yields/_implied_term_structure.pxd
+++ b/quantlib/termstructures/yields/_implied_term_structure.pxd
@@ -1,8 +1,8 @@
-from quantlib.handle cimport Handle
+from quantlib._handle cimport Handle
 from quantlib.time._date cimport Date
 from .._yield_term_structure cimport YieldTermStructure
 
-cdef extern from 'ql/termstructures/yield/impliedtermstructure.hpp' namespace 'QuantLib':
+cdef extern from 'ql/termstructures/yield/impliedtermstructure.hpp' namespace 'QuantLib' nogil:
     cdef cppclass ImpliedTermStructure(YieldTermStructure):
         ImpliedTermStructure(const Handle[YieldTermStructure]&,
                              const Date& referenceDate)
diff --git a/quantlib/termstructures/yields/_piecewise_zerospreaded_termstructure.pxd b/quantlib/termstructures/yields/_piecewise_zerospreaded_termstructure.pxd
index 00b7bedba..c17538066 100644
--- a/quantlib/termstructures/yields/_piecewise_zerospreaded_termstructure.pxd
+++ b/quantlib/termstructures/yields/_piecewise_zerospreaded_termstructure.pxd
@@ -1,5 +1,5 @@
 from libcpp.vector cimport vector
-from quantlib.handle cimport Handle
+from quantlib._handle cimport Handle
 from quantlib.time._date cimport Date
 from quantlib.time._daycounter cimport DayCounter
 from quantlib.time.frequency cimport Frequency
@@ -9,7 +9,7 @@ from quantlib._quote cimport Quote
 from quantlib.math._interpolations cimport Linear
 from quantlib.compounding cimport Compounding
 
-cdef extern from 'ql/termstructures/yield/piecewisezerospreadedtermstructure.hpp' namespace 'QuantLib':
+cdef extern from 'ql/termstructures/yield/piecewisezerospreadedtermstructure.hpp' namespace 'QuantLib' nogil:
     cdef cppclass InterpolatedPiecewiseZeroSpreadedTermStructure[I](YieldTermStructure):
         InterpolatedPiecewiseZeroSpreadedTermStructure(
             const Handle[YieldTermStructure]&,
diff --git a/quantlib/termstructures/yields/_rate_helpers.pxd b/quantlib/termstructures/yields/_rate_helpers.pxd
index 4ad4b6716..5aa8838b1 100644
--- a/quantlib/termstructures/yields/_rate_helpers.pxd
+++ b/quantlib/termstructures/yields/_rate_helpers.pxd
@@ -11,7 +11,7 @@ include '../../types.pxi'
 
 from libcpp cimport bool
 
-from quantlib.handle cimport Handle
+from quantlib._handle cimport Handle
 from quantlib.ext cimport shared_ptr
 from quantlib._quote cimport Quote
 from quantlib.time._calendar cimport BusinessDayConvention, Calendar
diff --git a/quantlib/termstructures/yields/_zero_spreaded_term_structure.pxd b/quantlib/termstructures/yields/_zero_spreaded_term_structure.pxd
index 251f6095a..8a48723cd 100644
--- a/quantlib/termstructures/yields/_zero_spreaded_term_structure.pxd
+++ b/quantlib/termstructures/yields/_zero_spreaded_term_structure.pxd
@@ -1,5 +1,5 @@
 from libcpp.vector cimport vector
-from quantlib.handle cimport Handle
+from quantlib._handle cimport Handle
 from quantlib.time._date cimport Date
 from quantlib.time._daycounter cimport DayCounter
 from quantlib.time.frequency cimport Frequency
@@ -9,7 +9,7 @@ from quantlib._quote cimport Quote
 from quantlib.math._interpolations cimport Linear
 from quantlib.compounding cimport Compounding
 
-cdef extern from 'ql/termstructures/yield/zerospreadedtermstructure.hpp' namespace 'QuantLib':
+cdef extern from 'ql/termstructures/yield/zerospreadedtermstructure.hpp' namespace 'QuantLib' nogil:
     cdef cppclass ZeroSpreadedTermStructure(YieldTermStructure):
         ZeroSpreadedTermStructure(
             const Handle[YieldTermStructure]&,