>=</span> <span class="n">where</span><span class="o">.</span><span
            class="n">suc</span>
        <span class="n">first</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span
            class="n">first</span>
        <span class="n">last</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span
            class="n">last</span>

        <span class="n">s</span> <span class="o">=</span> <span class="bp">self</span><span class="o">