class output_descr :Creates a?blocking:bool -> ?start_pos_out:int -> Unix.file_descr ->raw_out_channel
raw_out_channel for the passed file descriptor, which must
be open for writing.
The pos_out method returns logical positions, i.e. it counts the number
of written octets. It is not tried to determine the real file position.
The method close_out also closes the file descriptor.
blocking : Whether the channel waits until it can output if it is not
possible to write to the (non-blocking) descriptor. Defaults to true.start_pos_out : The position to which pos_out is initialized when
the channel is created, by default 0