def build_unique_fragments(self):
        """
        Find all possible fragment combinations of the MoleculeGraphs (in other
        words, all connected induced subgraphs)

        :return:
        """
        self.set_node_attributes()

        graph = self.graph.to_undirected()

        nm = iso.categorical_node_match("specie", "ERROR")

        # find all possible fragments, aka connected induced subgraphs
        all_fragments = []
        for ii in range(1, len(self.molecule)):
            for combination in combinations(graph.nodes, ii):
                subgraph = nx.subgraph(graph, combination)
                if nx.is_connected(subgraph):
                    all_fragments.append(subgraph)

        # narrow to all unique fragments using graph isomorphism
        unique_fragments = []
        for fragment in all_fragments:
            if not [nx.is_isomorphic(fragment, f, node_match=nm)
                    for f in unique_fragments].count(True) >= 1:
                unique_fragments.append(fragment)

        # convert back to molecule graphs
        unique_mol_graphs = []
        for fragment in unique_fragments:
            mapping = {e: i for i, e in enumerate(sorted(fragment.nodes))}
            remapped = nx.relabel_nodes(fragment, mapping)

            species = nx.get_node_attributes(remapped, "specie")
            coords = nx.get_node_attributes(remapped, "coords")

            edges = {}

            for from_index, to_index, key in remapped.edges:
                edge_props = fragment.get_edge_data(from_index, to_index, key=key)

                edges[(from_index, to_index)] = edge_props

            unique_mol_graphs.append(self.with_edges(Molecule(species=species,
                                                              coords=coords,
                                                              charge=self.molecule.charge),
                                                     edges))
        return unique_mol_graphs
Find all possible fragment combinations of the MoleculeGraphs (in other
        words, all connected induced subgraphs)

        :return: