iv>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span> </div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span>  <span class="keyword">protected</span>:</div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span>    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> U&gt;</div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span>    <span class="key