Description:

Grouch is a system for describing and enforcing a Python object
schema. An object schema describes every class in a collection of
objects -- in particular, it specifies the type of every instance
attribute of every class. Grouch includes a type language for
specifying attribute types, a tool to parse specially-formatted class
docstrings and output a complete object schema, and another tool for
walking a persistent object graph and ensuring that every scrap of
data in it conforms to the object schema extracted from your class
docstrings. The API for defining, querying, and enforcing types is
fairly complete and well-documented, so you can use Grouch's type
system in other ways as well.