docs: def check_required(self):
          """ Check all required settings have been provided
          """
          die = False
          for key, value in self.spec.items():
              if not getattr(self, key.upper()) and value['required']:
                  print(f"{key} is a required setting. "
                        "Set via command-line params, env or file. "
                        "For examples, try '--generate' or '--help'.")
                  die = True
          if die:
              sys.exit(1)