PY3.E1135

Unsupported membership test

Emitted when an instance in membership test expression doesn't implement membership protocol ( contains / iter / getitem ).

Noncompliant Code:

Copy
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)

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