const file_info *find(const filename &to_check) const;
//!< locates the record of information for the filename "to_check".
/*!< do not modify the returned object. it contains the current state
const file_info *find(const filename &to_check) const;
//!< locates the record of information for the filename "to_check".
/*!< do not modify the returned object. it contains the current state