from time import sleep_ms
from servo import Servo
my_servo = Servo(pin_id=28)
while True:
my_servo.write(90)
sleep_ms(500)
my_servo.write(0)
sleep_ms(500)
my_servo.write(180)
my_servo.write(90)
sleep_ms(500)
my_servo.write(90)
sleep_ms(500)