ures of <code>boost::asio::async_write()</code> not provided here</h3>
<p >We have (consciously) made these concessions:</p><ul>
<li><code>payload_blob</code> is a single blob. <code>async_write()</code> is templated in such a way as to accept that or a <em>sequence</em> of <code>Blob_const</code>s, meaning it supports scatter/gather.</li>
<li>There are also fancier advanced-async-flow-control overloads of <code>async_write()</code> with more features we haven't replicated. However the simplest overload onl