append(each:_:)

For each element of the provided collection, invoke the given generator and queue the returned future. Return a future whose value is an array containing the result of each generated future in the same order as the original sequence. The resulting array is intended to have semantics substantially similar to those provided by EventLoop.flatten(_:on:).

func append<S, Value>(each seq: S, _ generator: @escaping (S.Element) -> EventLoopFuture<Value>) -> EventLoopFuture<[Value]> where S : Sequence