import machine
import time

R = machine.Pin(18, machine.Pin.OUT)
G = machine.Pin(19, machine.Pin.OUT)
B = machine.Pin(20, machine.Pin.OUT)

while True:
    R.value(1)
    G.value(0)
    B.value(0)
    time.sleep(1)
    
    R.value(0)
    G.value(1)
    B.value(0)
    time.sleep(1)
    
    R.value(0)
    G.value(0)
    B.value(1)
    time.sleep(1)
    
    R.value(0)
    G.value(0)
    B.value(0)
    time.sleep(1)