 class=special>&lt;&lt;</span><span class=identifier>std</span><span class=special>::</span><span class=identifier>endl</span><span class=special>;</span>
    <span class=special>++</span><span class=identifier>p</span><span class=special>.</span><span class=identifier>first</span><span class=special>;</span>
  <span class=special>}</span>
<span class=special>}</span>
</pre></blockquote>

<p>
Note that hashing is automatically taken care of: <code>boost::hash</code> is
specialized to hash a composite key as