ss="bp">self</span><span class="o">.</span><span class="n">_check_heap_invariant</span><span
            class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">root</span><span
            class="p">)</span></div>

    <span class="k">def</span> <span class="nf">_check_heap_invariant</span><span class="p">(</span><span class="bp">self</span><span
            class="p">,</span> <span class="n">node</span><span class="p">):</span>
        <span class="k">if</span> <span class="n