pan> <span class="nb">float</span> <span class="o">=</span> <span class="kc">None</span><span class="p">,</span>
                        <span class="n">max_critical</span><span class="p">:</span> <span class="nb">float</span> <span class="o">=</span> <span class="kc">None</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="n">Signal</span><span class="p">:</span>
<span class="w">    </span><span class="sd">&quot;&quot;&quot;Builds a simple signal with a float value, string units, and o