Create a simple program in main.py:

from time import sleep
from cubloc import Output, High, Low
 
# LED on GP25, configured as an output
LED = 25
Output(LED)
 
while True:
    # Turn LED on for 500ms
    High(LED)
    print("LED ON")
    sleep(0.5)
 
    # Turn LED off for 500ms
    Low(LED)
    print("LED OFF")
    sleep(0.5)

This toggles the onboard LED every 500 ms.