import time
from machine import Pin, Timer

led1 = Pin(19, Pin.OUT)    # create output pin for LED 1
led2 = Pin(21, Pin.OUT)    # create output pin for LED 2
led3 = Pin(22, Pin.OUT)    # create output pin for LED 3
led4 = Pin(23, Pin.OUT)    # create output pin for LED 4

leds = [led1, led2, led3, led4]  # Define of all LED pins

def blink_leds(delay):
    while True:  
        for led in leds:
            led.value(not led.value())
            time.sleep_ms(delay)

blink_leds(200)