from enum import EnumMeta, IntEnum
 
 
class DefaultEnumMeta(EnumMeta):
    def __call__(cls, value=None, *args, **kwargs):
        if value is None:
            # Assume the first enum member is default
            return next(iter(cls))
        return super().__call__(value, *args, **kwargs)
 
 
class MyEnum(IntEnum, metaclass=DefaultEnumMeta):
    A = 0
    B = 1
    C = 2
 
 
assert MyEnum() is MyEnum.A
assert MyEnum(0) is MyEnum.A
assert MyEnum(1) is not MyEnum.A

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