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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 collapse(self):
 """ Collapse into a StridedInterval instance. :return: A new StridedInterval instance. """


        if self.cardinality:
            r = None
            for si in self._si_set:
                r = r._union(si) if r is not None else si

            return r

        else:
            # This is an empty StridedInterval...
            return StridedInterval.empty(self._bits)