class="n">node</span><span class="p">,</span> <span class="n">N</span><span
            class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">E</span><span
            class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">x_parent</span><span
            class="o">=</span><span class="mi">0</span><span class="p">,</span> <span class="n">y_parent</span><span
            class="o">=</span><span class="mi">0</span><span class="p">):</span>
     