def to_s(*)
      doc = REXML::Document.new
      decl = REXML::XMLDecl.new("1.0", "utf-8")
      doc.add decl
      doc.add_element @elem
      doc.to_s
    end
def to_s(*)
      doc = REXML::Document.new
      decl = REXML::XMLDecl.new("1.0", "utf-8")
      doc.add decl
      doc.add_element @elem
      doc.to_s
    end
Convert to XML-Document and return it as string