cial">;</span>
  <span class="keyword">typedef</span> <span class="keyword">void</span>                     <span class="identifier">value_type</span><span class="special">;</span>
  <span class="keyword">typedef</span> <span class="keyword">void</span>                     <span class="identifier">difference_type</span><span class="special">;</span>
  <span class="keyword">typedef</span> <span class="keyword">void</span>                     <span class="identifier">pointer</span><span class="special">;</spa