code: def from_xyzt_string(xyzt_string):
          
          symmop = SymmOp.from_xyz_string(xyzt_string.rsplit(',', 1)[0])
          try:
              time_reversal = int(xyzt_string.rsplit(',', 1)[1])
          except:
              raise Exception("Time reversal operator could not be parsed.")
          return MagSymmOp.from_symmop(symmop, time_reversal)
docs: Args:
              xyz_string: string of the form 'x, y, z, +1', '-x, -y, z, -1',
                  '-2y+1/2, 3x+1/2, z-y+1/2, +1', etc.
          Returns:
              MagSymmOp object