__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.)