class REXML::Element

def __to_xpath_helper node
  rv = node.expanded_name.clone
  if node.parent
    results = node.parent.find_all {|n|
      n.kind_of?(REXML::Element) and n.expanded_name == node.expanded_name
    }
    if results.length > 1
      idx = results.index( node )
      rv << "[#{idx+1}]"
    end
  end
  rv
end