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.

def open_ring(mol_graph, bond, opt_steps):
    """
    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.
    """
    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)