code: def _repr_label_vector(self, label_vector):
          
  
          string = ["1"]
          for cross_terms in label_vector:
              sub_string = []
              for index, order in cross_terms:
                  _ = self.grid_points.dtype.names[index]
                  if order > 1:
                      sub_string.append("{0}^{1}".format(_, order))
                  else:
                      sub_string.append(_)
              string.append(" * ".join(sub_string))
          return " + ".join(string)
docs: Return a human-readable representation of the Cannon label vector.
          
          label_vector should be [[(1,2), (2,1)], [(1,3)]] etc.