The __cmp__ method
__cmp__(self, other)
Called by comparison operations if rich comparison (see above) is not
defined. Should return a negative integer if self < other, zero
if self == other, a positive integer if self > other. If no
__cmp__, __eq__ or __ne__ operation is defined,
class instances are compared by object identity (address
). See
also the description of __hash__ for some important notes on
creating objects which support custom comparison operations and are
usable as dictionary keys. (Note: the restriction that exceptions are
not propagated by __cmp__ has been removed since Python 1.5.)
