ass="special">)</span>
        <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span>
<span class="special">);</span>
</pre>
<p>
          we choose to <code class="computeroutput"><span class="identifier">fail</span></code> in our
          example for the <code class="computeroutput"><span class="identifier">Action</span></code>:
          Quit and fail. Return a no_match (false). It can be one of:
        </p>
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