code: def yn(self, prompt, default=None):
          
          if default is True:
              opts = " [Y/n]: "
          elif default is False:
              opts = " [y/N]: "
          else:
              opts = " [y/n]: "
          prompt += opts
          return self.input(curry(filter_yn, default=default), prompt)
docs: Prompts the user for yes/no confirmation, with optional default