# mode: run class plop(object): def __init__(self): pass class testobj(object): def __init__(self): pass def __eq__(self, other): return plop() def test_equals(x): """ >>> x = testobj() >>> result = test_equals(x) >>> isinstance(result, plop) True >>> test_equals('hihi') False >>> test_equals('coucou') True """ eq = x == 'coucou' # not every str equals returns a bool ... return eq