title: Roadrunner RPC call log
body: <p>I want to call roadrunners RPC method log from PHP.</p>
  <p>I have an instance of <code>Spriral\Goridge\RPC</code> in <code>$rpc</code> and it is connected to the running roadrunner rpc via TCP. On that RPC instance I execute the following call, where <code>$payload</code> is a normal string. also tried with php array or json string and tried different flags for the third argument (<code>Relay::PAYLOAD_RAW</code>, <code>Relay::PAYLOAD_CONTROL</code> etc.)</p>
  <pre class="lang-php prettyprint-override"><code>$rpc-&gt;call('log', $payload);
  </code></pre>
  <p>but I always get this error message:</p>
  <pre><code>Spiral\Goridge\Exceptions\ServiceException: error 'rpc: service/method request ill-formed: log' on 'tcp://127.0.0.1:6001' in /var/www/vendor/spiral/goridge/src/RPC.php:123
  </code></pre>
  <p>I cannot find any documentation about it, but the log RPC method is there, just need to know how to format the <code>$payload</code> and if required which <code>$flags</code> to add as thrid argument.</p>