import neopixel
from machine import Pin
from time import sleep
from random import randrange as r
nl = 32
leds = neopixel.NeoPixel(Pin(4), nl)

while True:
    #leds.fill([0,0,0])
    col1 = [r(100,255),r(100,255),r(100,255) ]
    col2 = [r(100,255),r(100,255),r(100,255) ]
    for l in range(nl):
        leds[l] = col1
        if l >= 16:
            leds[l] = col2
        sleep(0.1)
        leds.write()
    
    for l in range(nl//2):
        leds[l+nl//2] = col1
        if l < 16:
            leds[nl//2 - l - 1] = col2
        sleep(0.1)
        leds.write()