microPython button irq debouncing

button_test.py

import time

from micropython import const
from machine import Pin, Timer

BUTTON_A_PIN = const(32)
BUTTON_B_PIN = const(33)

class Button:
    """
    Debounced pin handler

    usage e.g.:

    def button_callback(pin):
        print("Button (%s) changed to: %r" % (pin, pin.value()))

    button_handler = Button(pin=Pin(32, mode=Pin.IN, pull=Pin.PULL_UP), callback=button_callback)
    """

    def __init__(self, pin, callback, trigger=Pin.IRQ_FALLING, min_ago=300):
        self.callback = callback
        self.min_ago = min_ago

        self._blocked = False
        self._next_call = time.ticks_ms() + self.min_ago

        pin.irq(trigger=trigger, handler=self.debounce_handler)

    def call_callback(self, pin):
        self.callback(pin)

    def debounce_handler(self, pin):
        if time.ticks_ms() > self._next_call:
            self._next_call = time.ticks_ms() + self.min_ago
            self.call_callback(pin)
        #else:
        #    print("debounce: %s" % (self._next_call - time.ticks_ms()))
        
        
def button_a_callback(pin):
    print("Button A (%s) changed to: %r" % (pin, pin.value()))


def button_b_callback(pin):
    print("Button B (%s) changed to: %r" % (pin, pin.value()))


button_a = Button(pin=Pin(BUTTON_A_PIN, mode=Pin.IN, pull=Pin.PULL_UP), callback=button_a_callback)
button_b = Button(pin=Pin(BUTTON_B_PIN, mode=Pin.IN, pull=Pin.PULL_UP), callback=button_b_callback)

Unfortunately, the debouncing according to the script above did not work in my application.
So I'm using the "Switch debouncing" instead, as described here.