eturn right away. Know that upon that return the handler's captured state will be freed, as in all cases.</li>
<li><code>E</code> will never indicate would-block.</li>
</ul>
</li>
<li><code>on_sent_or_error()</code> is canceled and not called at all, such as possibly when <code>stop()</code>ing the underlying <code>Task_engine</code>. This is similar to the aforementioned <code>operation_aborted</code> situation. Know that upon that return the handler's captured state <em>will</em> be freed at the time of w