code: def coord_list_mapping_pbc(subset, superset, atol=1e-8):
      
      atol = np.array([1., 1. ,1.]) * atol
      return cuc.coord_list_mapping_pbc(subset, superset, atol)
docs: Gives the index mapping from a subset to a superset.
      Superset cannot contain duplicate matching rows
  
      Args:
          subset, superset: List of frac_coords
  
      Returns:
          list of indices such that superset[indices] = subset