from machine import Pin
from utime import sleep

led_onboard = Pin(25, Pin.OUT)  # Assuming onboard LED is connected to GP25.  Adjust if different.
led_external = Pin(5, Pin.OUT) # Assuming external LED is connected to GP5. Adjust if different.

while True:
    led_onboard.value(1)  # Turn onboard LED ON
    led_external.value(1) # Turn external LED ON
    sleep(5)

    led_onboard.value(0)  # Turn onboard LED OFF
    led_external.value(0) # Turn external LED OFF
    sleep(5)