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();

  Function tf_function;
  PartialTensorShape unknown_shape;
  TaggedValue signature(unknown_shape, DT_FLOAT);
  Status s = tf_function.RegisterTrace(std::move(trace), signature, signature);
  ASSERT_TRUE(s.ok()) << s.message();
  TaggedValue args = TaggedValue::Tuple();
  args.tuple().emplace_back(TaggedValue(x));
  args.tuple().emplace_back(TaggedValue(x));
  StatusOr<TaggedValue> v = tf_function.Execute(ctx_.get(), args);

inline TaggedValue::Type TypeToTaggedType<String>() {
  return TaggedValue::Type::STRING;
}
/// Retrieves tagged type of Callable handle.
template <>
inline TaggedValue::Type TypeToTaggedType<Callable>() {
  return TaggedValue::Type::FUNC;
}
/// Retrieves tagged type of Integer handle.
template <>
inline TaggedValue::Type TypeToTaggedType<Integer>() {
  return TaggedValue::Type::INT64;
}
/// Retrieves tagged type of Float handle.