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

pixel = NeoPixel(Pin(13),16)

def sweep(color, delay= 0.01):
    for i in range(len(pixel)-1, -1, -1):
        pixel[i] = color
        pixel.write()
        sleep(delay)

while True:
    sweep((0,255, 0))

    sweep((255, 0, 0))

    sweep((0, 0, 255))

    sweep((255, 255, 0))

    sweep((0, 255, 255))

    sweep((255, 0, 255))