def set_group_bond(self, atom_index_one, atom_index_two, bond_order):
raise NotImplementedError<EOL>
Add bonds within a group.
        :param atom_index_one: the integer atom index (in the group) of the first partner in the bond
        :param atom_index_two: the integer atom index (in the group) of the second partner in the bond
        :param bond_order: the integer bond order