def METHOD_NAME(self):
    if not (self.reg_read(STATUS) & (TX_DS | MAX_RT)):
        return None  # tx not finished
    # either finished or failed: get and clear status flags, power down
    status = self.reg_write(STATUS, RX_DR | TX_DS | MAX_RT)
    self.reg_write(CONFIG, self.reg_read(CONFIG) & ~PWR_UP)
    return 1 if status & TX_DS else 2