from machine import Pin
from time import sleep
switch_1 = (4,Pin.IN,Pin.PULL_DOWN)
switch_2 = (5,Pin.IN,Pin.PULL_DOWN)
switch_3 = (6,Pin.IN,Pin.PULL_DOWN)
led_sw1 = Pin(1,Pin.OUT)
led_sw2 = Pin(2,Pin.OUT)
led_sw3 = Pin(3,Pin.OUT)
while True:
    if switch_1.value == 1:
        led_sw1.value(1)
        sleep(1)
        led_sw1.value(0)
        sleep(1)
        if switch_2.value == 1:
           led_sw1.value(1)
           sleep(1)
           led_sw2.value(0)
        sleep(1)
           if switch_3.value == 1:
             led_sw1.value(1)
             sleep(1)
             led_sw3.value(0)
             sleep(1)
             print("end of nested loop")