LispEngine.Lexing.Scanner.isDigit C# (CSharp) Method

        private bool isDigit()
        {
            return more() && char.IsDigit(peek());
        }

 private static TokenType?unsignedNumber(Scanner s)
 {
     if (!s.isDigit())
     {
         return(null);
     }
     while (s.isDigit())
     {
         s.readChar();
     }
     if (s.isExponent())
     {
         return(readExponent(s));
     }
     if (s.peek() != '.')
     {
         return(TokenType.Integer);
     }
     return(remainingFloat(s));
 }