docs: def ask(message, options):
      """Ask the message interactively, with the given possible responses"""
      while 1:
          if os.environ.get('PIP_NO_INPUT'):
              raise Exception('No input was expected ($PIP_NO_INPUT set); question: %s' % message)
          response = raw_input(message)
          response = response.strip().lower()
          if response not in options:
              print('Your response (%r) was not one of the expected responses: %s' % (
                  response, ', '.join(options)))
          else:
              return response