code: def open_ring(mol_graph, bond, opt_steps):
      
      obmol = BabelMolAdaptor.from_molecule_graph(mol_graph)
      obmol.remove_bond(bond[0][0]+1, bond[0][1]+1)
      obmol.localopt(steps=opt_steps)
      return MoleculeGraph.with_local_env_strategy(obmol.pymatgen_mol, OpenBabelNN(), reorder=False, extend_structure=False)
docs: Function to actually open a ring using OpenBabel's local opt. Given a molecule
      graph and a bond, convert the molecule graph into an OpenBabel molecule, remove
      the given bond, perform the local opt with the number of steps determined by
      self.steps, and then convert the resulting structure back into a molecule graph
      to be returned.