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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 repertoire(self, direction, mechanism, purview):
 """Return the cause or effect repertoire based on a direction. Args: direction (Direction):
 |CAUSE| or |EFFECT|. mechanism (tuple[int]):
 The mechanism for which to calculate the repertoire. purview (tuple[int]):
 The purview over which to calculate the repertoire. Returns: np.ndarray: The cause or effect repertoire of the mechanism over the purview. Raises: ValueError: If ``direction`` is invalid. """

        if direction == Direction.CAUSE:
            return self.cause_repertoire(mechanism, purview)
        elif direction == Direction.EFFECT:
            return self.effect_repertoire(mechanism, purview)

        return validate.direction(direction)