Python 2.5 quick reference

To test whether some class C1 is a subclass of another class C2, use this predicate:

issubclass(C1, C2)

Examples:

>>> class Polygon:
...     pass
... 
>>> class Square(Polygon):
...     pass
... 
>>> issubclass(Square, Polygon)
True
>>> issubclass(Polygon, Square)
False
>>> issubclass(Square, Square)
True
>>> issubclass(unicode, basestring)
True