quotes = ('A man is not complete until he is married. Then he is finished.',

          'As I said before, I never repeat myself.',

          'Behind a successful man is an exhausted woman.',

          'Black holes really suck...', 'Facts are stubborn things.')

class QuoteModel:

    def get_quote(self, n):

        try:

            value = quotes[n]

        except IndexError as err:

            value = 'Not found!'

        return value

class QuoteTerminalView:

    def show(self, quote):

        print('And the quote is: "{}"'.format(quote))

    def error(self, msg):

        print('Error: {}'.format(msg))

    def select_quote(self):

        return input('Which quote number would you like to see?')

class QuoteTerminalController:

    def __init__(self):

        self.model = QuoteModel()

        self.view = QuoteTerminalView()

    def run(self):

        valid_input = False

        while not valid_input:

            n = self.view.select_quote()

            try:

                n = int(n)

            except ValueError as err:

                self.view.error("Incorrect index '{}'".format(n))

            else:

                valid_input = True

        quote = self.model.get_quote(n)

        self.view.show(quote)

def main():

    controller = QuoteTerminalController()

    while True:

        controller.run()

if __name__ == '__main__':

    main()