title: Boost PropertyTree: check if child exists
body: <p>I'm trying to write an XML parser, parsing the XML file to a <code>boost::property_tree</code> and came upon this problem. How can I check (quickly) if a child of a certain property exists?</p>
  
  <p>Obviously I could iterate over all children using <code>BOOST_FOREACH</code> - however, isn't there a better solution to this?</p>