def METHOD_NAME():
  cb_ops = sub_lattice_tools.generate_cb_op_up_to_order(7)
  mats = sub_lattice_tools.generate_matrix_up_to_order(7)
  base_group = sgtbx.space_group_info( "P 2 2 2" ).group()
  for cb_op, mat in zip(cb_ops, mats):
    rat_cb_op = mat
    extended_group=None
    try:
      extended_group = sgtbx.space_group_info( "P 2 2 2 (%s)"%cb_op ).group()
    except Exception: pass
    rbg = construct_rational_point_group( base_group, rat_cb_op )
    reg = None
    if extended_group is not None:
      reg = construct_rational_point_group( extended_group )
      assert compare_groups(reg, rbg)