Emoji game with 2 sec timer alert and round function

#adding a 20 second timer with round function
import os
from random import shuffle, randint
from guizero import App, Box, Picture, PushButton, Text, warn

def counter():
    timer.value = int(timer.value) - 1
    if int(timer.value) == 0:
        timer.cancel(counter)
        # reset the timer
        result.value = "Game Over"
        warn("Time Out", "you've run out of time")
        # reset timer
        timer.value = "20"
        # reset result
        result.value = ""
        # start new round
        setup_round()
        #restart timer
        timer.repeat(1000, counter)
        round_number()

def round_number():
    rounds.value = int(rounds.value) +1


# set the path to the emoji folder on your computer
emojis_dir = "emojis"
# create a list of the locations of the emoji images
emojis = [os.path.join(emojis_dir, f) for f in os.listdir(emojis_dir) if os.path.isfile(os.path.join(emojis_dir, f))]
# shuffle the emojis
shuffle(emojis)

def match_emoji(matched):
    if matched:
        result.value = "correct"
    else:
        result.value = "incorrect"

    setup_round()

def setup_round():
    # for each picture and button in the list assign an emoji to its image feature
    for picture in pictures:
        # make the picture a random emoji
        picture.image = emojis.pop()

    for button in buttons:
        # make the image feature of the PushButton a random emoji
        button.image = emojis.pop()
        # set the command to be called and pass False, as these emoji wont be the matching ones
        button.update_command(match_emoji, [False])

    # choose a new emoji
    matched_emoji = emojis.pop()

    # select a number at random
    random_picture = randint(0,8)
    # change the image feature of the Picture with this index in the list of pictures to the new emoji
    pictures[random_picture].image = matched_emoji

    random_button = randint(0,8)
    # change the image feature of the PushButton with this index in the list of buttons to the new emoji
    buttons[random_button].image = matched_emoji
    # set the command to be called and pass True, as this is the matching emoji
    buttons[random_button].update_command(match_emoji, [True])


# setup the app
app = App("emoji match")

result = Text(app)

# create a box to house the grids
game_box = Box(app)
# create a box to house the pictures
pictures_box = Box(game_box, layout="grid", align="left")
# create a box to house the buttons
buttons_box = Box(game_box, layout="grid", align="right")

# create the an empty lists to add the buttons and pictures to
buttons = []
pictures = []
# create 9 PushButtons with a different grid coordinate and add to the list
for x in range(0,3):
    for y in range(0,3):
        # put the pictures and buttons into the lists
        picture = Picture(pictures_box, grid=[x,y])
        pictures.append(picture)

        button = PushButton(buttons_box, grid=[x,y])
        buttons.append(button)


# add in the extra features
extra_features = Box(app)
timer_label = Text(extra_features, text="Countdown: ", align="left")
timer = Text(extra_features, text="Get Ready", align="left")
rounds = Text(extra_features, text=1, align="right")
rounds_label = Text(extra_features, text="Round: ", align="right")



setup_round()

# start the timer
timer.value = 20
timer.repeat(1000,counter)
rounds.value = 1

app.display()