microbit Blinkenlights
A tiny snippet of code often used when the microbit is not showing anything specifically on the screen but you want to indicate that something is happening in the background - like it's broadcasting on radio.
# Microbit Blinkenlights
from microbit import *
blink_interval = 500
pixel_intensity = 9
while True:
display.set_pixel(2, 2, pixel_intensity)
pixel_intensity = 0 if pixel_intensity == 9 else 9
sleep(blink_interval)
It turns the centre pixel of the display on and off at a frequency decided by the polling interval.