from machine import Pin
from time import sleep
from neopixel import NeoPixel
from random import randint

leds = 16

pixels = NeoPixel(Pin(15),leds)

while True:
    l = leds
    while l > 0:
        r = randint(0,255)
        b = randint(0,255)
        g = randint(0,255)
        rgb = (r,g,b)
        for i in range(l):
            if i != 0:
                pixels[i-1] = (0,0,0)
            pixels[i] = (rgb)
            pixels.write()
            sleep(0.1)
        l -= 1
    if l == 0:
        sleep(0.3)
        pixels.fill((0,0,0))
        pixels.write()
        sleep(0.3)