def METHOD_NAME(self):
    def callback(n):
        print("called")
        return np.array([1], dtype=np.complex64)
    print("init", hackrf.init())
    print("open", hackrf.open())
    print("start_tx", hackrf.start_tx_mode(callback))
    time.sleep(1)
    print("stop_tx", hackrf.stop_tx_mode())
    print("close", hackrf.close())
    print("exit", hackrf.exit())