fold
inline fun <T : Any, R : Any> Iterable<Data<T>>.foldToData(initial: R, coroutineContext: CoroutineContext = EmptyCoroutineContext, meta: Meta = Meta.EMPTY, crossinline block: suspend (result: R, data: ValueWithMeta<T>) -> R): Data<R>
inline fun <T : Any, R : Any> DataSet<T>.foldToData(initial: R, coroutineContext: CoroutineContext = EmptyCoroutineContext, meta: Meta = Meta.EMPTY, crossinline block: suspend (result: R, data: NamedValueWithMeta<T>) -> R): Data<R>