public void TextNavigator_LookAhead_2()
        {
            const string  text      = "ABC";
            TextNavigator navigator = new TextNavigator(text);

            Assert.AreEqual('C', navigator.LookAhead(2));
            navigator.ReadChar();
            Assert.AreEqual(TextNavigator.EOF, navigator.LookAhead(2));
            navigator.ReadChar();
            Assert.AreEqual(TextNavigator.EOF, navigator.LookAhead(2));
            navigator.ReadChar();
            Assert.AreEqual(TextNavigator.EOF, navigator.LookAhead(2));
        }