Analyzes modules for data models and draws diagram in graphviz dot format.

Analogue of the tool modelviz/graph_models for django.

Usage:

1. put the script into appengine sdk
2. run the script from your app directory: python path/to/modelviz.py module_names > models.dot
3. convert .dot file into png (or whatever you like): dot models.dot -Tpng > models.png
4. watch something like this:

Script understands db.Model, db.Expando, db.polymodel.PolyModel subclasses, and recognize reference properties.