How to stop a function

A simple return statement will ‘stop’ or return the function; in precise terms, it ‘returns’ function execution to the point at which the function was called – the function is terminated without further action.

That means you could have a number of places throughout your function where it might return. Like this:

def player():
    # do something here
    check_winner_variable = check_winner()  # check something 
    if check_winner_variable == '1': 
        return
    second_test_variable = second_test()
    if second_test_variable == '1': 
        return
       
    # let the computer do something
    computer()