def Default(self, arg, value):
    """Adds a line which sets the default value for an optional arg."""
    # If you do "@default foo=[bar]" it's implied that [bar] precedes [foo] in
    # the argument list -- hence, we parse value before arg.
    self._ParseArgs(value)
    # The arg is assumed optional, since it can default to things.
    if self._optional_args not in arg:
      self._optional_args.append(arg)
    self.paragraphs.SetType(paragraph.DefaultLine, arg, value)
dataset/ETHPy150Open google/vimdoc/vimdoc/block.py/Block.Default/swapped operands of `not in`