="special">::</span><span class="identifier">position_tagged</span></code> which provides positional
        information that we can use to tell the AST's position in the input stream
        anytime. We will need these information for error handling and reporting.
      </p>
<p>
        Like before, we need to tell <a href="../../../../../../../libs/fusion/doc/html/index.html" target="_top">Boost.Fusion</a>
        about our structs to make them first-class fusion citizens that the grammar
        can util