Red Black Tree and Multimap
<p>In many compilers, Data structures such as<code>Set</code>, <code>Map</code>, <code>Multimap</code> use Red-Black-Trees in behind. And a <code>multimap</code> stores multiple and duplicated keys.</p>

<blockquote>
  <p>"A red-black-tree stores keys uniquely and binds just one DataValue to
  each key"</p>
</blockquote>

<ol>
<li>Is above statement true?</li>
<li>If that is true, How we can use a red-black-tree to implement a <code>multimap</code> (as C++ STL did)?</li>
</ol>
