ass="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span>    <span class="keywordflow">return</span> mt_.build_tree();</div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span>  }</div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span> </div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span>  <span class="keywordtype">void</span> open(<a class="code hl_struct" href="structproofs_1_1_mer