public Not(DragonToken tok, Express x2) : base(tok, x2, x2) { }
public And(DragonToken tok, Express x1, Express x2) : base(tok, x1, x2) { }
public Relation(DragonToken tok, Express x1, Express x2) : base(tok, x1, x2) { }
public Do() { ex = null; st = null; }
public While() { expr = null; stmt = null; }
public Access(Id a, Express i, DragonType p) : base(new DragonWord("[]", DragonTag.INDEX), p) { array = a; index = i; }