Python program fails to run (pane is dead) using AWS Cloud9

I am new too python and had some basic programs earlier work flawlessly. However this simple lottery generator is failing too compile. I have little errors with indentation that I fixed but it still fails to run. Below is my code for this project. I am having trouble seeing where or why this will not run correctly.

import random 
def main():
    print('**** Welcome to the Pick-3, Pick-4 lottery number generator *********')
    print('Select from the following menu:')
    displayMenu()
    menu=int(input())
    while(menu==1 or menu==2):
        displaySelection(menu)
        print(lotteryNumber(menu))
        displayMenu()
        menu=int(input())

        displaySelection(menu)
        print('Thanks for trying the Lottery Application.')
        print('*********************************************************')

def displayMenu():
    print('Select from the following menu:')
    print('1. Generate 3-Digit Lottery number')
    print('2. Generate 4-Digit Lottery number')
    print('3. Exit the Application')
    return

def displaySelection(selected):
    if (selected ==1):
        print('You selected 1. The following 3-digit lottery number was generated:')
    elif(selected==2):
        print('You selected 2. The following 4-digit lottery number was generated:')
    else:
        print('You selected 3.')
        return

def lotteryNumber(menu):
    ran=''
    digits=3 if menu==1 else 4
    while digits>0:
        ran=ran+str(random.randint(0,9))
        digits=digits-1
        return ran

    if __name__ =='__main__':
        main()