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();
    CopyIntoUnion(v);
    return *this;
  }
  /// TaggedValue constructor for type TENSOR.
  explicit TaggedValue(TaggedValueTensor tensor)