PY3.E1135
Unsupported membership test
Emitted when an instance in membership test expression doesn't implement membership protocol ( contains / iter / getitem ).
Noncompliant Code:
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                                                class Foo:
    def __init__(self, numbers):
        self.numbers = numbers
foo = Foo([1, 2, 3, 4])
print(1 in foo)
Compliant Code:
Copy
                                                    
                                                
                                            class Foo:
    def __init__(self, numbers):
        self.numbers = numbers
    def __contains__(self, value):
        return value in self.numbers
foo = Foo([1, 2, 3, 4])
print(1 in foo)