Package tracing provides tracing of sent and received 9P messages.
Decoder creates a new styxproto.Decoder that traces messages received on r.
Encoder creates a new styxproto.Encoder that traces messages before writing them to w.
A Func can be used to access 9P messages as they pass through a styxproto.Encoder or a styxproto.Decoder. Messages are not copied; a TraceFn should not modify msg, and msg should not be accessed after the TraceFn returns.