EitherN, but beter

EitherN.kt

sealed class Either2<A, B> {

    data class Op1<A>(val value: A) : Either2<A, Nothing>()
    data class Op2<B>(val value: B) : Either2<Nothing, B>()

}

sealed class Either3<A, B, C> : Either2<A, B>() {
    
    data class Op3<C>(val value: C) : Either3<Nothing, Nothing, C>()
    
}

sealed class Either4<A, B, C, D> : Either3<A, B, C>() {
    
    data class Op4<D>(val value: D) : Either4<Nothing, Nothing, Nothing, D>()
    
}