pan class="special">::</span><span class="identifier">string</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">payload</span><span class="special">,</span>
    <span class="identifier">frame</span><span class="special">::</span><span class="identifier">opcode</span><span class="special">::</span><span class="identifier">value</span> <span class="identifier">op</span> <span class="special">=</span> <span class="identifier">frame</span><span class="special">