er, building up as we go.
          When comparing EBNF to <a href="http://boost-spirit.com" target="_top">Spirit</a>,
          the expressions may seem awkward at first. <a href="http://boost-spirit.com" target="_top">Spirit</a>
          heavily uses operator overloading to accomplish its magic.
        </p>
<h6>
<a name="spirit.qi.tutorials.warming_up.h0"></a>
          <span class="phrase"><a name="spirit.qi.tutorials.warming_up.trivial_example__1_parsing_a_number"></a></span><a class="link" href="warm