div class="line"><a name="l00073"></a><span class="lineno">   73</span>&#160;    CHECK_GE(num_nodes, 0);</div>
<div class="line"><a name="l00074"></a><span class="lineno">   74</span>&#160;    num_nodes_ = num_nodes;</div>
<div class="line"><a name="l00075"></a><span class="lineno">   75</span>&#160;    class_.resize(num_nodes_);</div>
<div class="line"><a name="l00076"></a><span class="lineno">   76</span>&#160;    class_size_.assign(num_nodes_, 1);</div>
<div class="line"><a name="l00077"></a><span class=