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))

        Value index_to_i64 = rewriter.create<arith::IndexCastOp>(
            op.getLoc(), rewriter.getI64Type(), slice_size_index);
        Value i64_to_tensor = rewriter.create<tensor::FromElementsOp>(
            op.getLoc(),
            tensorflow::GetTypeFromTFTensorShape({1}, rewriter.getI64Type()),
            index_to_i64);
        slice_sizes_values.push_back(i64_to_tensor);