code: function ListNode (children) {
      for(var i = 0; i < children.length; i++)
          this[i] = children[i];
      this.length = children.length;
  }
docs: AST node representing a list
  e.g. for constructors with variable number of arguments, e.g. in
  Call(Var("alert"), [Num("10"), Num("11")])