code: def _call_validators(self):
          
          msg = []
          msg.extend(self._validate_keyfile())
          msg.extend(self._validate_dns_zone())
          msg.extend(self._validate_retries())
          msg.extend(self._validate_project())
          return msg
docs: Actually run all the validations.
  
          Returns:
              list(str): Error messages from the validators.