prompt.py

def prompt(question, answers):
    """
    Prompt the user with a question and only accept defined answers.
    
    Input:
        question (str): Question string
        answers (list): A list containing accpeted response value
    Output:
        answer (str|int): Provided answer
    """
    print question

    # Print a numbered list of answers
    for i in range(len(answers)):
        print ' %d. %s' % (i+1, answers[i])

    while True:
        choice = raw_input(">>> ")

        try:
            choice = int(choice)
            answer = answers[choice-1]
        # A ValueError is raised when a string is cast to an int
        except ValueError:
            print "Invalid input."
        # An IndexError is raise when the list index is out of range
        except IndexError:
            print "Invalid input."
        else:
            # Lists can be indexed with negative numbers
            if choice < 1:
                print "Invalid input."
                continue
            break

    return answer