public static partial class ExtensionMethods { static public string MyToString<T>(this T s) { return "<" + s.ToString() + ">"; } }or
public static partial class ExtensionMethods { static public string MyToString(this object s) { return "<" + s.ToString() + ">"; } }Here's one that applies to all classes which implement IEquatable< T >
public static partial class ExtensionMethods { public static bool InList<T>(this T s, params T[] list) where T : IEquatable<T> { return list.Contains(s); } }