Micropython adding game

adding.py

import microbit

firstnum = microbit.random(4)
secondnum = microbit.random(5)

microbit.display.scroll('{} + {}'.format(firstnum, secondnum), 200)

def wait_for_pressed():
    while 1:
        buttona = microbit.button_a.is_pressed()
        buttonb = microbit.button_b.is_pressed()
        if buttona or buttonb:
            break
        
    while microbit.button_a.is_pressed() or microbit.button_b.is_pressed() :
        pass
    
    if buttona:
        return 'a'
    else:
        return 'b' 

def count():
    answer = 0
    while 1:
        if wait_for_pressed() == 'a':
            answer +=1
            microbit.display.print(str(answer))
            
        else:
            break
        
    if answer == firstnum + secondnum:
        microbit.display.print(microbit.Image.HAPPY)
    else:
        microbit.display.print(microbit.Image.SAD)
        
    return answer
    
count()