l">&amp;</span> <span class="identifier">n</span></code>) that adds the numbers parsed. On a successful
        parse, this number is the sum of all the parsed numbers.
      </p>
<p>
        The first <code class="computeroutput"><span class="identifier">double_</span></code> parser
        attaches this action:
      </p>
<pre class="programlisting"><span class="special">[&amp;](</span><span class="keyword">auto</span><span class="special">&amp;</span> <span class="identifier">ctx</span><span class="speci