>class</span>, <span class="keyword">class</span>&gt; <span class="keyword">class </span>Unit,
<a name="l00278"></a>00278         <span class="keyword">class </span>Root
<a name="l00279"></a>00279     &gt;
<a name="l00280"></a><a class="code" href="a00196.html">00280</a>     <span class="keyword">class </span>GenLinearHierarchy&lt;NullType , Unit, Root&gt;
<a name="l00281"></a>00281         : <span class="keyword">public</span> Root <span class="comment">// is this better: Unit&lt;NullType, Root&gt; ?</span