from machine  import Pin
import utime

red = Pin(16, Pin.OUT)
green = Pin(18, Pin.OUT)
blue = Pin(20, Pin.OUT)

while True:
  red.value(0)
  green.value(1)
  blue.value(1)
  utime.sleep(1)
  red.value(1)
  green.value(0)
  blue.value(1)
  utime.sleep(1)
  red.value(1)
  green.value(1)
  blue.value(0)
  utime.sleep(1)