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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def deserialize_rfc(attr):
 """Deserialize RFC-1123 formatted string into Datetime object. :param str attr: response string to be deserialized. :rtype: Datetime :raises: DeserializationError if string format invalid. """

        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