Maybe monad encoding in C#

Maybe.cs

class Nothing : Exception {}

public static class Maybe {
  public static void Nothing() => throw new Nothing();
  public static void Guard(bool cond) { if (!cond) Nothing(); }
  public static void GuardNot(bool cond) { if (cond) Nothing(); }
}

public static class TryParse {
  public static UInt32 UInt32(string x) {
    UInt32 parsed;
    Maybe.Guard(System.UInt32.TryParse(x, out parsed));
    return parsed;
  }
}

public static class Status {
  static Tuple<char,string> FirstCharAndRest(string x) {
    Maybe.Guard(x.Length > 0);
    return Tuple.Create(x[0], x.Substring(1, x.Length-1));
  }
  
  static string TruncateAt(char c, string x) {
    var index = x.IndexOf(c);
    Maybe.Guard(index >= 0);
    return index > 0 ? x.Substring(0, index) : "";
  }
  
  static Tuple<string,string> SplitInTwo(char c, string x) {
    var xs = x.Split(c);
    Maybe.Guard(xs.Length == 2);
    return Tuple.Create(xs[0], xs[1]);
  }
  
  public static Tuple<UInt32,UInt32> Parse(string s) {
    Maybe.GuardNot(s == null);
    var firstCharAndRest = FirstCharAndRest(s);
    Maybe.Guard(firstCharAndRest.Item1 == '[');
    var xOfY = TruncateAt(']', firstCharAndRest.Item2);
    var xAndY = SplitInTwo('/', xOfY);
    var x = TryParse.UInt32(xAndY.Item1);
    var y = TryParse.UInt32(xAndY.Item2);
    return Tuple.Create(x, y);
  }
}

void Main()
{
  try {
    var x = Status.Parse("[3/32] Monads!!");
    Console.WriteLine($"{x.Item1} of {x.Item2}");
  }
  catch (Nothing) {
    Console.WriteLine("Unable to parse.");
  }
}