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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 reset(self):
 """ Reset the internal node traversal state. Must be called prior to visiting future nodes. :return: None """


        self._sorted_nodes.clear()
        self._node_to_index.clear()
        self._reached_fixedpoint.clear()

        for i, n in enumerate(self.sort_nodes()):
            self._node_to_index[n] = i
            self._sorted_nodes.add(n)