n class="special">::</span><span class="identifier">value_type</span> <span class="identifier">header_type</span><span class="special">;</span>
  <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">string</span><span class="special">&lt;</span><span class="identifier">Tag</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">string_type</span><span class="special">;</span>

  <span class="identifier">headers_con