n class="identifier">date_type</span> <span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.12.15.3.20.3.4"></a><h2>Description</h2>
<p>This class provides the skeleton for the creation of iterators. New and interesting interators can be created by plugging in a new function that derives the next value from the current state. generation of various types of 