code: def enable_shifted_1(self):
          
          self._require_version(major=2)
          self.config_flag('STRONG_PW2', True)
          self.config_flag('SEND_REF', True)
docs: This will cause a shifted character 1 (typically '!') to be sent before
          anything else. This can be used to make the YubiKey output qualify as a
          password with 'special characters', if such is required.
  
          Because of the way this is stored in the config flags, it is not
          possible to disable this option once it is enabled (of course, you
          can abort config update or reprogram the YubiKey again).
  
          Requires YubiKey 2.x.