{};
    </span><span class=keyword>struct </span><span class=identifier>unary_parser_category        </span><span class=special>: </span><span class=identifier>plain_parser_category </span><span class=special>{};
    </span><span class=keyword>struct </span><span class=identifier>action_parser_category       </span><span class=special>: </span><span class=identifier>unary_parser_category </span><span class=special>{};</span></pre>
<h2>embed_t</h2>
<p>Each parser has a typedef <tt>embed_t</tt>. This typedef 