public override Value call(Env env, Value [] args)
        {
            Value   oldThis    = env.setThis(getThis());
            Closure oldClosure = env.setClosure(this);

            try {
                return(_fun.callClosure(env, args, _args));
            }
            finally {
                env.setClosure(oldClosure);
                env.setThis(oldThis);
            }
        }