class IdCompared:

    '''A value that's compared using `is` instead of ==.

    Do not use this for strings as they are interned, causing `is` to have the

    same meaning as ==.

    '''

    def __init__(self, value): self.value = value

    def __eq__(self, other):

        return (other != None and other.__class__ == self.__class__

            and other.value is self.value)

    def __hash__(self): return id(self.value)