code: def near_reduce(self, coords_set, threshold=1e-4):
          
          unique_coords = []
          coords_set = [self.slab.lattice.get_fractional_coords(coords)
                        for coords in coords_set]
          for coord in coords_set:
              if not in_coord_list_pbc(unique_coords, coord, threshold):
                  unique_coords += [coord]
          return [self.slab.lattice.get_cartesian_coords(coords)
                  for coords in unique_coords]
docs: Prunes coordinate set for coordinates that are within
          threshold
  
          Args:
              coords_set (Nx3 array-like): list or array of coordinates
              threshold (float): threshold value for distance