public sealed class Either<F, S>
where F : class
where S : class

Public NotInheritable Class Either(Of F As Class, S As Class)

generic<typename F, typename S>
where F : ref class
where S : ref class
public ref class Either sealed

[<SealedAttribute>]
type Either<'F, 'S when 'F : not struct when 'S : not struct> =  class end