public void TextNavigator_IsSymbol_1()
        {
            const string  text      = "$A+";
            TextNavigator navigator = new TextNavigator(text);

            Assert.IsTrue(navigator.IsSymbol());
            navigator.ReadChar();
            Assert.IsFalse(navigator.IsSymbol());
            navigator.ReadChar();
            Assert.IsTrue(navigator.IsSymbol());
        }