self.flatMap { .reduce(into: [], $0.map(transform), on: eventLoop) { $0.append($1) } }

9:58 AM

public static func reduce<InputValue>(_ initialResult: Value, _ futures: [EventLoopFuture<InputValue>], on eventLoop: EventLoop, _ nextPartialResult: @escaping (Value, InputValue) -> Value) -> EventLoopFuture<Value> {

9:58 AM

ほんとだ。