utf8_iterator utf8_iterator::end(const std::string& str) { return utf8_iterator(str.end(), str.end()); }
inline utf8_iterator utf8_end (void) const { return (utf8_iterator (end())); }
utf8_iterator utf8_iterator::begin(std::string const &str) { return utf8_iterator(str.begin(), str.end()); }
inline utf8_iterator utf8_begin (void) const { return (utf8_iterator (begin())); }