from time import sleep 
from machine import Pin

def motor (a,b,c,d,z):
    a1.value(a),b1.value(b),a2.value(c),b2.value(d)
    sleep (z)

a1=Pin(23,Pin.OUT)
a2=Pin(21,Pin.OUT)
b1=Pin(22,Pin.OUT)
b2=Pin(19,Pin.OUT)


while(1):
    motor (1,1,0,0, 0.2)
    motor (0,1,1,0, 0.2)
    motor (0,0,1,1, 0.2)
    motor (1,0,0,1, 0.2)