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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def assert_is_not_substring(substring, subject, message=None, extra=None):
 """Raises an AssertionError if substring is a substring of subject."""

    assert (
        (subject is not None)
        and (substring is not None)
        and (subject.find(substring) == -1)
    ), _assert_fail_message(message, substring, subject, "is in", extra)