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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 dissimilarity_metric(self, a, b):
 """Return non-zero if references to this module are strange, and should be drawn extra-long. The value defines the length, in rank. This is also good for putting some vertical space between seperate subsystems. Returns an int between 1 (default) and 4 (highly unrelated). """

        # if self._is_pylib(a) and self._is_pylib(b):
        #     return 1

        res = 4
        for an, bn, n in zip_longest(a.name_parts, b.name_parts, list(range(4))):
            res -= an == bn
            if n >= 3:
                break
        return res