
  -type mode() ::
            read | write | append | exclusive | raw | binary |
            {delayed_write,
             Size :: non_neg_integer(),
             Delay :: non_neg_integer()} |
            delayed_write |
            {read_ahead, Size :: pos_integer()} |
            read_ahead | compressed |
            {encoding, unicode:encoding()} |
            sync.

  There is no documentation for mode/0
