Resumes I/O on msg.
Use this to resume after calling [[email protected]_message], or after adding a new chunk to a chunked response.
I/O won't actually resume until you return to the main loop.
This must only be called on a [class@ServerMessage] which was created by the Server and are
currently doing I/O, such as those passed into a [callback@ServerCallback] or emitted in a [signal@Server:SoupServer:request-read
] signal.
| this |
a Server |
| msg |
a ServerMessage associated with this. |