In [138]: class bad(object):
def __init__(self, str):
self._str = str
def __repr__(self):
return repr(self._str)
def __hash__(self):
return 1
.....:
In [145]: set([bad("cat"), bad("dog"), bad("fish")])
Out[145]: set(['cat', 'fish', 'dog'])
In [146]: [hash(i) for i in set([bad("cat"), bad("dog"), bad("fish")])]
Out[146]: [1, 1, 1]