dentifier">data_type</span><span class="special">;</span>                 
  <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">pair</span><span class="special">&lt;</span> <span class="keyword">const</span> <span class="identifier">DomainT</span><span class="special">,</span> <span class="identifier">CodomainT</span> <span class="special">&gt;</span>                                                                            <a nam