e</span><span class="special">&gt;</span><span class="special">&amp;</span><span class="special">)</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Signature1<span class="special">,</span> <span class="keyword">typename</span> Signature2<span class="special">&gt;</span> 
    <span class="keyword">void</span> <a class="link" href="../boost/function.html#id-1_3_17_6_2_1_4_32_2_5-bb"><span class="keyword">operator