// op is not a `tf.TensorList*` op, return empty, although this case
// should never be trigged in practice since patterns are only applied
// on `tf.TensorList*` ops.
std::optional<ConstBytesAttr> CustomOptions(MLIRContext* context,
                                            mlir::Operation* op) {
  if (auto reserve =
          llvm::dyn_cast_or_null<mlir::TF::TensorListReserveOp>(op)) {
    tflite::TensorType tflite_type =