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# A contains everything
class A:
def __contains__(self, key):
return True
a = A()
print(True in a)
print(1 in a)
print(() in a)
# B contains given things
class B:
def __init__(self, items):
self.items = items
def __contains__(self, key):
return key in self.items
b = B([])
print(1 in b)
b = B([1, 2])
print(1 in b)
print(2 in b)
print(3 in b)
class C:
def __contains__(self, arg):
return arg
print(C().__contains__(0))
print(C().__contains__(1))
print(C().__contains__(''))
print(C().__contains__('foo'))
print(C().__contains__(None))
print(0 in C())
print(1 in C())
print('' in C())
print('foo' in C())
print(None in C())
print(0 not in C())
print(1 not in C())
print('' not in C())
print('foo' not in C())
print(None not in C())
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