463bf2760f89" title="Short-hand for flow::Error_code which is very common.">Error_code()</a></code> if non-null. This indicates 1 or more (<code>N</code>) bytes of the buffer, and the handle, were sent successfully. If <code>N != payload_blob.size()</code>, then the remaining bytes cannot currently be sent without blocking and should be tried later. (Informally: Consider <a class="el" href="namespaceipc_1_1transport_1_1asio__local__stream__socket.html#a68071e53f4a048084f8ad26ff3ac6711" title="boost.asio ext