code: def set_lookup_method(xml_root, value):
      
      if xml_root.tag == "testsuites":
          _set_property(xml_root, "polarion-lookup-method", value)
      elif xml_root.tag in ("testcases", "requirements"):
          _set_property(xml_root, "lookup-method", value)
      else:
          raise Dump2PolarionException(_NOT_EXPECTED_FORMAT_MSG)
docs: Changes lookup method.