code: def add_cell_argument(self, name, help, required=False):
      
  
      for action in self._actions:
        if action.dest == name:
          raise ValueError('Arg "%s" was added by add_argument already.' % name)
  
      self._cell_args[name] = {'required': required, 'help': help}
docs: Add a cell only argument.
  
      Args:
        name: name of the argument. No need to start with "-" or "--".
        help: the help string of the argument.
        required: Whether it is required in cell content.