public override void ExitRule(IParseTreeListener listener)
        {
            IArithmeticListener typedListener = listener as IArithmeticListener;

            if (typedListener != null)
            {
                typedListener.ExitVariable(this);
            }
        }
        public override void EnterRule(IParseTreeListener listener)
        {
            IArithmeticListener typedListener = listener as IArithmeticListener;

            if (typedListener != null)
            {
                typedListener.EnterScientific(this);
            }
        }