func backup(filename string) error {
	if DO_BACKUP {
		if _, ok := _FILES_BACKUPED[filename]; !ok {
			if err := file.Backup(filename); err != nil {
				return err
			}
			_FILES_BACKUPED[filename] = struct{}{}
		}
	}
	return nil
}
func backup(filename string) error {
	if DO_BACKUP {
		if _, ok := _FILES_BACKUPED[filename]; !ok {
			if err := file.Backup(filename); err != nil {
				return err
			}
			_FILES_BACKUPED[filename] = struct{}{}
		}
	}
	return nil
}
func backup ( filename string ) error { if DO_BACKUP { if _ , ok := _FILES_BACKUPED [ filename ] ; ! ok { if err := file . Backup ( filename ) ; err != nil { return err } _FILES_BACKUPED [ filename ] = struct { } { } } } return nil }
// backup does a backup of a file.
backup does a backup of a file .