          <span class="n">node</span><span class="o">.</span><span class="n">suc</span><span class="o">.</span><span
            class="n">pred</span> <span class="o">=</span> <span class="n">node</span><span class="o">.</span><span
            class="n">pred</span>
        <span class="k">if</span> <span class="n">node</span><span class="o">.</span><span class="n">pred</span><span
            class="p">:</span>
            <span class="n">node</span><span class="o">.</span><span class="n">pred</span><span 