ace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">property_tree</span> <span class="special">{</span>
    <span class="keyword">class</span> <a class="link" href="../boost/property_tree/ptree_error.html" title="Class ptree_error">ptree_error</a><span class="special">;</span>
    <span class="keyword">class</span> <a class="link" href="../boost/property_tree/ptree_bad_data.html" title="Class ptree_bad_data">ptree_