 class="p">,</span> <span class="n">y_coord_t</span><span class="p">)</span> <span class="k">const</span><span class="p">;</span>
  <span class="n">y_iterator</span>        <span class="n">Loc</span><span class="o">::</span><span class="n">y_at</span><span class="p">(</span><span class="n">x_coord_t</span><span class="p">,</span> <span class="n">y_coord_t</span><span class="p">)</span> <span class="k">const</span><span class="p">;</span>
  <span class="n">Loc</span>               <span class="n">Loc</span><