 a valid
iterator of some index of <code>*this</code> (i.e. does not refer to some
other <code>multi_index_container</code>.)<br>
<b>Effects:</b> Returns an <code>nth_index&lt;N>::type::iterator</code> 
equivalent to <code>it</code>.<br>
<b>Complexity:</b> Constant.<br>
<b>Exception safety:</b> <code>nothrow</code>.
</blockquote>

<code>template&lt;int N,typename IteratorType><br>
typename nth_index&lt;N>::type::const_iterator project(IteratorType it)const;</code>

<blockquote>
<b>Requires:</b> <code>0 &lt;