code: def strip_dbm_tx_power(self, idx):
          
          idx = Radiotap.align(idx, 1)
          dbm_tx_power, = struct.unpack_from('<b', self._rtap, idx)
          return idx + 1, dbm_tx_power
docs: strip(1 byte) dbm_tx_power
          :return: int
              idx
          :return: int