    </span><span class=identifier>sequenced</span><span class=special>&lt;&gt;,                               </span><span class=comment>// list-like index
    </span><span class=identifier>ordered_non_unique</span><span class=special>&lt;</span><span class=identifier>identity</span><span class=special>&lt;</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>string</span><span class=special>&gt; </span><span class=special>&gt; </span><span class=comment>// words by alp