code: def describe_features(self, traj):
          
          feature_descs = []
          # fill in the atom indices using just the first frame
          self.partial_transform(traj[0])
          top = traj.topology
  
          aind_tuples = [self.atom_indices for _ in range(self.sliced_reference_traj.n_frames)]
          zippy = zippy_maker(aind_tuples, top)
  
          zippy = itertools.product(["LandMarkFeaturizer"], ["RMSD"], [self.sigma], zippy)
  
          feature_descs.extend(dict_maker(zippy))
  
          return feature_descs
docs: Return a list of dictionaries describing the LandmarkRMSD features.
  
          Parameters
          ----------
          traj : mdtraj.Trajectory
              The trajectory to describe
  
          Returns
          -------
          feature_descs : list of dict
              Dictionary describing each feature with the following information
              about the atoms participating in each feature
                  - resnames: unique names of residues
                  - atominds: the four atom indicies
                  - resseqs: unique residue sequence ids (not necessarily
                    0-indexed)
                  - resids: unique residue ids (0-indexed)
                  - featurizer: Alpha Angle
                  - featuregroup: the type of dihedral angle and whether sin or
                    cos has been applied.