self._emit_with_loc(' : (!tfr.tensor_list, i64) -> !tfr.tensor')
    # load the op def of tf.Pack
    self._op_defs.lookup('Pack')
    return casted, TFRTypes.TENSOR

  def _index_to_I64(self, value, ty):
    if ty == TFRTypes.INDEX:
      casted = self._ssa_name('casted')
      self._emit_with_loc('\n{} = arith.index_cast {} : index to i64'.format(
          casted, value))