span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span
            class="n">first</span>
        <span class="n">euler_tour</span> <span class="o">=</span> <span class="p">[</span><span
            class="n">first</span><span class="o">.</span><span class="n">data</span><span class="p">]</span>
        <span class="n">current</span> <span class="o">=</span> <span class="n">first</span><span
            class="o">.</span><span class="n">suc</span>
        <span class="n">cnt</span