function cleanup() {
	var err;
	var f;
	if ( arguments.length ) {
		f = arguments[ 0 ];
	} else {
		f = TMP;
	}
	err = unlinkSync( f );
	if ( err ) {
		throw err;
	}
}
Removes a temporary file.

@private
@param {string} [f] - filename
@throws {Error} unexpected error