from machine import Pin
from time import sleep

r = Pin(15, Pin.OUT) 
g = Pin(2, Pin.OUT) 
b = Pin(4, Pin.OUT) 

while True:
  r.on() 
  sleep(2)
  r.off()
  g.on()
  sleep(2)
  g.off()
  b.on()
  sleep(2)
  b.off()