import tkinter
import tkinter.font
import random
key = ''
ch = ''
def key_down(e):
global key
key = e.keysym
def key_up(e):
global key
key = ''
def set_ch():
global ch
ch = chr(random.randint(97, 122))
label['text'] = ch
def main_proc():
if key == ch:
set_ch()
root.after(100, main_proc)
root = tkinter.Tk()
root.geometry('100x100')
root.bind('<KeyPress>', key_down)
root.bind('<KeyRelease>', key_up)
label_font = tkinter.font.Font(size=30)
label = tkinter.Label(font=label_font)
label.pack()
main_proc()
root.mainloop()