code: def deserialize_rfc(attr):
          
          if isinstance(attr, ET.Element):
              attr = attr.text
          try:
              date_obj = datetime.datetime.strptime(
                  attr, "%a, %d %b %Y %H:%M:%S %Z")
              if not date_obj.tzinfo:
                  date_obj = date_obj.replace(tzinfo=TZ_UTC)
          except ValueError as err:
              msg = "Cannot deserialize to rfc datetime object."
              raise_with_traceback(DeserializationError, msg, err)
          else:
              return date_obj
docs: Deserialize RFC-1123 formatted string into Datetime object.
  
          :param str attr: response string to be deserialized.
          :rtype: Datetime
          :raises: DeserializationError if string format invalid.