class="op">=</span> <span class="va">pol</span><span class="op">$</span><span class="va">y</span><span class="op">)</span>
        <span class="op">)</span>
        <span class="kw">if</span> <span class="op">(</span><span class="fu"><a href="https://rdrr.io/r/base/any.html">any</a></span><span class="op">(</span><span class="va">hover_within_flow</span><span class="op">)</span><span class="op">)</span> <span class="op">{</span>
          <span class="co"># Find the alluvium that is plotted on top. (last)</