StreamClass.uniq<S>(source: Source<S>): StreamClass<Exclude<S, AnyFailure>, Extract<S, AnyFailure>>
StreamClass#uniq as a static: Stream.uniq(source, …) is
Stream.from(source).uniq(…).
await Stream.uniq([1, 1, 2, 1]).collect(); // [1, 2]
StreamClass<Exclude<S, AnyFailure>, Extract<S, AnyFailure>>