class Nokogiri::XML::Node

def canonicalize(mode=XML::XML_C14N_1_0,inclusive_namespaces=nil,with_comments=false)
  c14n_root = self
  document.canonicalize(mode, inclusive_namespaces, with_comments) do |node, parent|
    tn = node.is_a?(XML::Node) ? node : parent
    tn == c14n_root || tn.ancestors.include?(c14n_root)
  end
end