Copy or Alias?

Implement two small types and a probe — the test asserts what each assignment did: ``csharp public struct ValuePoint { public int X; } /* value: copies */ public sealed class RefPoint { public int X; } /* reference: aliases */ /* increments X and returns the (copied) struct — the caller's copy must NOT be affected */ static ValuePoint BumpValue(ValuePoint p); /* increments X through the reference — the caller's object MUST be affected, and the same instance is returned */ static RefPoint BumpRef(RefPoint p); ``