BackupQueue             An R6 Class for managing backups (abstract base
                        class)
BackupQueueDate         An R6 class for managing datestamped backups
BackupQueueDateTime     An R6 class for managing timestamped backups
BackupQueueIndex        An R6 class for managing indexed backups
Cache                   An R6 class for managing a persistent
                        file-based cache
DirectoryQueue          An R6 class for managing persistent file-based
                        queues (abstract base class)
backup_info             Discover existing backups
rotate                  Rotate or backup files
rotate_rds              Serialize R objects to disk (with backup)
