span>
        <span class="n">x_min</span> <span class="o">=</span> <span class="mi">0</span>
        <span class="n">x_max</span> <span class="o">=</span> <span class="mi">0</span>
        <span class="k">for</span> <span class="n">pos</span><span class="p">,</span> <span class="n">data</span> <span
            class="ow">in</span> <span class="n">N</span><span class="p">:</span>  <span class="c1"># Nodes are ordered as in a DFS traversal of the tree</span>
            <span class="n">label</span> <span cl