public PositiveNode(BaseNode right) { Right = right; }
public MinusNode(BaseNode left, BaseNode right) { Left = left; Right = right; }
//単項演算子なので、一つしか項を取らない。 public NegativeNode(BaseNode right) { Right = right; }
public DivideNode(BaseNode left, BaseNode right) { Left = left; Right = right; }
public MultiplyNode(BaseNode left, BaseNode right) { Left = left; Right = right; }