TaggedValue& operator=(TaggedValue&& v) {
    destroy();
    MoveIntoUnion(std::move(v));
    return *this;
  }
  /// Move constructor.
  TaggedValue(TaggedValue&& v) : type_(NONE) { MoveIntoUnion(std::move(v)); }
  /// Copy constructor.
  TaggedValue(const TaggedValue& v) : type_(NONE) { CopyIntoUnion(v); }
  /// Copy assignment operator.
  TaggedValue& operator=(const TaggedValue& v) {
    destroy();

  return call_op->Execute(outputs, &num_outputs);
}

Status VerifySupportedSignature(TaggedValue signature) {
  if (signature.type() == TaggedValue::Type::TENSOR_SPEC) {
    return ::tensorflow::OkStatus();
  }
  if (signature.type() == TaggedValue::Type::TUPLE) {
    for (const auto& t : signature.tuple()) {
      if (t.type() != TaggedValue::Type::TENSOR_SPEC) {
        break;
      }
    }
    return ::tensorflow::OkStatus();