|</span> <span class="kc">undefined</span><span class="p">,</span> <span class="nx">Action</span><span class="o">&gt;</span>

<span class="k">export</span> <span class="kd">function</span> <span class="nf">reducerFn</span><span class="p">(</span><span class="nx">current</span><span class="p">:</span> <span class="nx">State</span> <span class="o">|</span> <span class="kc">undefined</span><span class="p">,</span> <span class="nx">action</span><span class="p">:</span> <span class="nx">Action</span><span class=