from machine import Pin
from utime import sleep
button_fast=Pin(28,Pin.IN,Pin.PULL_DOWN)
button_slow=Pin(27,Pin.IN,Pin.PULL_DOWN)
led = Pin(0,Pin.OUT)
delay=1
step=1
def faster_rate():
    global delay
    delay=delay-step
    
def slower_rate():
    global delay
    delay=delay+step
while True:
    led.value(1)
    sleep(delay)
    led.value(0)
    sleep(delay)
   
button_fast.irq(handler=faster_rate,trigger=button_fast.IRQ_FALLING)
button_slow.irq(handler=slower_rate,trigger=button_slow.IRQ_FALLING)