I posted the following message to google groups (gnu.emacs.help) but I got no reply. Then I emailed Richard Stallman this message and he suggested that I send it to the following email address:
<snip>
Michael Abraham Shulman has written a coroutine feature for
Emacs at the following location.
https://www.emacswiki.org/emacs/coroutine.el
I am about to write a completely pre-emptive time-sharing system
but first I need to know if I will be re-inventing the wheel.
I hope my contribution to GNU Emacs is helpful for all the
programmers out there who agonize over GNUS busy waiting all the
time.
</snip>
--