an><span class="w"> </span><span class="cpf">&lt;nlohmann/json.hpp&gt;</span>
<span class="k">using</span><span class="w"> </span><span class="n">json</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">nlohmann</span><span class="o">::</span><span class="n">json</span><span class="p">;</span>

<span class="p">...</span>

<span class="w">    </span><span class="c1">// Subscribe to corresponding messages with handlers</span>
<span class="w">    </span><span class="n"