 of port errors, and the
exception is not caught locally, it will propagate out of
event-loop-run!.
</p>
<p>As an example of how to use a-sync-write-watch!, here is the
implementation of await-put-bytevector!:
</p><div class="example">
<pre class="example">(define await-put-bytevector! 
  (case-lambda
    ((await resume port bv) (await-put-bytevector! await resume #f port bv))
    ((await resume loop port bv)
     (define length (bytevector-length bv))
     (_throw-exception-if-regular-file (fileno port))

