A Direct_stream_writer.t is a simple object for responding to a Pipe_rpc query.
Direct_stream_writer.t
Pipe_rpc
write t x returns `Closed if t is closed, or `Flushed d if it is open. In the open case, d is determined when the message has been flushed from the underlying Transport.Writer.t.
write t x
`Closed
t
`Flushed d
d
Transport.Writer.t