et human-friendly, machinery of serializing/deserializing <code>Code</code>s. No such machinery exists for general <a class="el" href="namespaceipc.html#aa3192e586cc45d3e7c22463bf2760f89" title="Short-hand for flow::Error_code which is very common.">Error_code</a>, and specifying an <a class="el" href="namespaceipc.html#aa3192e586cc45d3e7c22463bf2760f89" title="Short-hand for flow::Error_code which is very common.">Error_code</a> in an input stream would probably invovle (at least) providing a numeric value