code: def describe_features(self, traj):
          n_f = self.partial_transform(traj).shape[1]
          zippy=zip(itertools.repeat("N/A", n_f),
                    itertools.repeat("N/A", n_f),
                    itertools.repeat("N/A", n_f),
                    itertools.repeat(("N/A","N/A","N/A","N/A"), n_f))
          return dict_maker(zippy)