code: def sort_orbitals(element_pdos):
      sorted_orbitals = ['s', 'p', 'py', 'pz', 'px',
                         'd', 'dxy', 'dyz', 'dz2', 'dxz', 'dx2',
                         'f', 'f_3', 'f_2', 'f_1', 'f_0', 'f1', 'f2', 'f3']
      unsorted_keys = element_pdos.keys()
      sorted_keys = []
      for key in sorted_orbitals:
          if key in unsorted_keys:
              sorted_keys.append(key)
      return sorted_keys