</span><span class="n">coord_t</span><span class="p">;</span>
      <span class="k">typename</span> <span class="n">iterator</span><span class="p">;</span> <span class="n">where</span> <span class="n">RandomAccessTraversalConcept</span><span class="o">&lt;</span><span class="n">iterator</span><span class="o">&gt;</span><span class="p">;</span> <span class="c1">// iterator along D-th axis.</span>
      <span class="n">where</span> <span class="n">iterator</span><span class="o">::</span><span class="n">value_