code: def aos_as_list(self):
          '''
          Returns a list of atomic orbitals, sorted from lowest to highest energy
          '''
          return sorted(chain.from_iterable(
              [self.aos[el] * int(self.composition[el]) for el in self.elements]
          ), key=lambda x: x[2]f aos_as_list(self):
          '''
          Returns a list of atomic orbitals, sorted from lowest to highest energy
          '''
          return sorted(chain.from_iterable(
              [self.aos[el] * int(self.composition[el]) for el in self.elements]
          ), key=lambda x: x[2])
docs: Returns a list of atomic orbitals, sorted from lowest to highest energy