namespace std::chrono {
  class link {
  public:
    link(link&&)            = default;
    link& operator=(link&&) = default;
    // unspecified additional constructors
    string_view name()   const noexcept;
    string_view target() const noexcept;
  };
}string_view name() const noexcept;
string_view target() const noexcept;