, timeouts and events
may subsequently be added or posted after event-loop-run! has
returned, and event-loop-run! then called for them.  This is thread
safe - any thread may call this procedure, including any callback or
task running on the event loop.  The &rsquo;loop&rsquo; argument is optional: this
procedure operates on the event loop passed in as an argument, or if
none is passed (or #f is passed), on the default event loop.  Applying
this procedure to an event loop does not change the blocking status 