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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 find_rings(self, including=None):
 """ Find ring structures in the MoleculeGraph. :param including: list of site indices. If including is not None, then find_rings will only return those rings including the specified sites. By default, this parameter is None, and all rings will be returned. :return: dict {index:cycle}. Each entry will be a ring (cycle, in graph theory terms) including the index found in the Molecule. If there is no cycle including an index, the value will be an empty list. """


        # Copies self.graph such that all edges (u, v) matched by edges (v, u)
        undirected = self.graph.to_undirected()
        directed = undirected.to_directed()

        cycles_nodes = []
        cycles_edges = []

        # Remove all two-edge cycles
        all_cycles = [c for c in nx.simple_cycles(directed) if len(c) > 2]

        # Using to_directed() will mean that each cycle always appears twice
        # So, we must also remove duplicates
        unique_sorted = []
        unique_cycles = []
        for cycle in all_cycles:
            if sorted(cycle) not in unique_sorted:
                unique_sorted.append(sorted(cycle))
                unique_cycles.append(cycle)

        if including is None:
            cycles_nodes = unique_cycles
        else:
            for i in including:
                for cycle in unique_cycles:
                    if i in cycle and cycle not in cycles_nodes:
                        cycles_nodes.append(cycle)

        for cycle in cycles_nodes:
            edges = []
            for i, e in enumerate(cycle):
                edges.append((cycle[i-1], e))
            cycles_edges.append(edges)

        return cycles_edges