(* Operations on file names *) val current_dir_name : string;        (* The conventional name for the current directory           (e.g. [.] in Unix). *)val concat : string -> string -> string;        (* [concat dir file] returns a file name that designates file           [file] in directory [dir]. *)val is_absolute : string -> bool;        (* Return [true] if the file name is absolute or starts with an           explicit reference to the current directory ([./] or [../] in           Unix), and [false] if it is relative to the current directory. *)val check_suffix : string -> string -> bool;        (* [check_suffix name suff] returns [true] if the filename [name]           ends with the suffix [suff]. *)val chop_suffix : string -> string -> string;        (* [chop_suffix name suff] removes the suffix [suff] from           the filename [name]. The behavior is undefined if [name] does not           end up with the suffix [suff]. *)val basename : string -> string;val dirname : string -> string;        (* Split a file name into directory name / base file name.           [concat (dirname name) (basename name)] returns a file name           which is equivalent to [name]. Moreover, after setting the           current directory to [dirname name] (with [sys__chdir]),           references to [basename name] (which is a relative file name)	   designate the same file as [name] before the call to [chdir]. *);;