ass="o">::</span><span class="n">xy_at</span><span class="p">(</span><span class="k">const</span> <span class="n">difference_type</span><span class="o">&amp;</span><span class="p">)</span> <span class="k">const</span><span class="p">;</span>

  <span class="c1">// x/y versions of all methods that can take difference type</span>
  <span class="n">x_iterator</span>        <span class="n">Loc</span><span class="o">::</span><span class="n">x_at</span><span class="p">(</span><span class="n">x_coord_t</span><span