fier">hpp</span><span class="special">&gt;</span></code>
      are defined inside <code class="computeroutput"><span class="keyword">namespace</span> <span class="identifier">boost</span></code>.
    </p>
<p>
      The class <code class="computeroutput"><span class="identifier">compressed_pair</span></code> is
      very similar to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span></code>, but if either of the template argument