I'm somewhat uneasy about having coprocs inaccessible to each other.
I can foresee reasonable cases where I'd want a coproc to utilize one or
more other coprocs.

In particular, I can see cases where a coproc is written to by one process,
and read from by another.

Can we at least have the auto-close behaviour be made optional, so that it
can be turned off when we want to do something more sophisticated?

-Martin