module' object has no attribute 'Heatmap' 

import heatmap
import random

if **name** == "**main**":
    pts = []
    for x in range(400):
        pts.append((random.random(), random.random() ))

```
print "Processing %d points..." % len(pts)

hm = heatmap.Heatmap()
img = hm.heatmap(pts)
img.save("classic.png")
```
