flatten
inline fun <Error, A> Iterable<Either<Error, A>>.flattenOrAccumulate(combine: (Error, Error) -> Error): Either<Error, List<A>>
Flatten a list of Either into a single Either with a list of values, or accumulates all errors using combine.
fun <Error, A> Iterable<Either<Error, A>>.flattenOrAccumulate(): Either<NonEmptyList<Error>, List<A>>
Flatten a list of Either into a single Either with a list of values, or accumulates all errors with into an NonEmptyList.