pan><span class="p">)</span> <span class="o">+</span> <span class="mi">1</span>
        <span class="n">chunk</span><span class="p">[</span><span class="bp">self</span><span class="o">.</span><span class="n">mid_i</span><span class="p">]</span> <span class="o">=</span> <span class="n">mid</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span>  <span class="o">+</span> <span class="s1">&#39;&#39;</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span c