nal.  The &rsquo;generator&rsquo; argument is a
procedure taking one argument, namely a yield argument (see the
documentation on the make-iterator procedure for further details).
This await-generator! procedure will run &rsquo;generator&rsquo;, and whenever
&rsquo;generator&rsquo; yields a value will cause &rsquo;proc&rsquo; to execute in the event
loop specified by the &rsquo;loop&rsquo; argument, or in the default event loop if
no &rsquo;loop&rsquo; argument is provided or #f is provided as the &rsquo;loo