Python Blynk-- can we STOP set_user_task function?

Hello all friends, Im a student doing a Blynk project on Raspberry Pi by using Python. One part of the project is an automatic electric fan which is based on the temperature. I have used the blynk.set_user_task function to run the control part, but this function is actually a non-stop periodic function, currently I just used some if statements to avoid printing the result when I turn the electric fan off. Here is my question, is there any way to stop the set_user_task function?

Here is part of my code


##add auto switch in the ducntion so when auto on, reading, off, manul control
def my_user_task():
    #print('loop')
    if GPIO.input(19): ## GPIO pin 19 is connected to GPIO pin 26
        humidity,temperature = Adafruit_DHT.read_retry(22, 4)
        print('Action 2')
        blynk.virtual_write(3, '{0:0.1f}'.format(temperature))
        print(temperature)
        blynk.virtual_write(5, '{0:0.1f}'.format(humidity))
        print(humidity)
        if temperature > 21.0:
            GPIO.output(FAN_PIN, GPIO.LOW)
            sleep(0.2)
        else:
            GPIO.output(FAN_PIN, GPIO.HIGH)
            sleep(0.2)

@blynk.VIRTUAL_WRITE(1)
def my_write_handler(value):		## change only the input changed
    if value == '1':
        print(value)
        GPIO.output(26, GPIO.HIGH)
        blynk.set_user_task(my_user_task,10000)
    elif value == '0':
        GPIO.output(26, GPIO.LOW)
        GPIO.output(FAN_PIN, GPIO.HIGH)

Iā€™m not sure but blynk._task = None will probably stop it. Alternatively you can change the ms_period to a very big value.