StreamClass.mapEvery<S>(source: Source<S>,every: number,fn: (value: Exclude<S, AnyFailure>) => Exclude<S, AnyFailure> | PromiseLike<Exclude<S, AnyFailure>>): StreamClass<Exclude<S, AnyFailure>, Extract<S, AnyFailure>>
StreamClass#mapEvery as a static: Stream.mapEvery(source, …) is
Stream.from(source).mapEvery(…).
await Stream.mapEvery([1, 2, 3, 4], 2, (n) => n * 10).collect(); // [10, 2, 30, 4]
StreamClass<Exclude<S, AnyFailure>, Extract<S, AnyFailure>>