from machine import Pin, ADC
from utime import sleep_ms

led_pins = [Pin(16, Pin.OUT), Pin(17, Pin.OUT), Pin(18, Pin.OUT), Pin(19, Pin.OUT)]
pot_pin = ADC(Pin(28))

def read_pot_value(): 

    pot_value = pot_pin.read_u16()
    return pot_value

def flash_leds(delay):  
    
    for led in led_pins:
        led.value(1)
    sleep_ms(delay)
    for led in led_pins:
        led.value(0)
    sleep_ms(delay)

while True:
    pot_value = read_pot_value()
    flash_leds(pot_value // 50)