Set the packet data

def _set_data(self, data):
        """Set the packet data"""
        if type(data) == bytearray:
            self._data = data
        elif type(data) == str:
            if sys.version_info < (3,):
                self._data = bytearray(data)
            else:
                self._data = bytearray(data.encode('ISO-8859-1'))
        elif type(data) == list or type(data) == tuple:
            self._data = bytearray(data)
        elif sys.version_info >= (3,) and type(data) == bytes:
            self._data = bytearray(data)
        else:
            raise Exception('Data must be bytearray, string, list or tuple,'
                            ' not {}'.format(type(data)))