extern void remove_unicode_bom (boost::optional<std::string>& line);
extern boost::optional<std::string> get_line_file (FILE* f);
extern boost::optional<std::string> get_line_string (std::string* s);
extern void remove_unicode_bom (boost::optional<std::string>& line);
extern boost::optional<std::string> get_line_file (FILE* f);
extern boost::optional<std::string> get_line_string (std::string* s);