import time
from machine import Pin

led_pins = [Pin(28, Pin.OUT), Pin(26, Pin.OUT), 
 Pin(21, Pin.OUT), Pin(16, Pin.OUT), Pin(7, Pin.OUT),
 Pin(5, Pin.OUT),  Pin(2, Pin.OUT), Pin(1, Pin.OUT)]

while True:
    for led in led_pins:
        led.value(1)
        time.sleep(0.1)
        led.value(0)