>y</span> <span class="o">*</span> <span class="n">_chunksize</span>
        <span class="n">b</span> <span class="o">=</span> <span class="nb">max</span><span class="p">(</span><span class="n">t</span> <span class="o">-</span> <span class="n">_chunksize</span><span class="p">,</span> <span class="n">bottom</span><span class="p">)</span>

        <span class="k">return</span> <span class="p">(</span><span class="n">l</span><span class="p">,</span> <span class="n">b</span><span class="p">,</span> <span class