">node</span><span class="o">.</span><span class="n">left</span><span
            class="p">:</span>
            <span class="k">assert</span> <span class="n">node</span><span class="o">.</span><span
            class="n">priority</span> <span class="o">&lt;=</span> <span class="n">node</span><span
            class="o">.</span><span class="n">left</span><span class="o">.</span><span class="n">priority</span>
            <span class="k">assert</span> <span class="bp">self</span><span class="o">.</span><span