    <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits&lt;Iterator&gt;::difference_type base_difference_type;
<a name="l00057"></a>00057     <span class="keyword">typedef</span> <span class="keyword">typename</span> SFn::difference_type                           difference_type;
<a name="l00058"></a>00058     <span class="keyword">typedef</span> <span class="keyword">typename</span> std::iterator_traits&lt;Iterator&gt;::reference       reference;
<a name="l00059"