extern bool operator==(dcp::LanguageTag const& a, dcp::LanguageTag const& b);
extern std::ostream& operator<<(std::ostream& os, dcp::LanguageTag const& tag);
extern bool operator==(dcp::LanguageTag const& a, dcp::LanguageTag const& b);
extern std::ostream& operator<<(std::ostream& os, dcp::LanguageTag const& tag);