import RPi.GPIO as GPIOimport time

pin = 2
refresh_period = 0.02

GPIO.setup(pin, GPIO.OUT)
GPIO.output(pin, True)

for i in range(1, 100):
  GPIO.output(pin, False)
  time.sleep(0.001)
  GPIO.output(pin, True)
  time.sleep(refresh_period)

time.sleep(1)

for i in range(1, 100):  
  GPIO.output(pin, False)
  time.sleep(0.002)
  GPIO.output(pin, True)
  time.sleep(refresh_period)

time.sleep(1)
for i in range(1, 100):
  GPIO.output(pin, False)
  time.sleep(0.0015)
  GPIO.output(pin, True)
  time.sleep(refresh_period)

time.sleep(1)