micropython-examples/pwm/rgb.py

from machine import Pin
from time import sleep

blue = Pin(0, Pin.OUT)
green = Pin(4, Pin.OUT)
red = Pin(5, Pin.OUT)

blue.off()
red.on()
sleep(1)
red.off()
green.on()
sleep(1)
green.off()
blue.on()
sleep(1)
blue.off()