public static IAsyncTransducer <TInput, TResult> Filtering <TInput, TResult>(
this IAsyncTransducer <TInput, TResult> transducer, Predicate <TResult> test) => transducer.AsyncCompose(Filtering(test));
public static IAsyncTransducer <TInput, TResult> Mapping <TInput, TMedium, TResult>(
this IAsyncTransducer <TInput, TMedium> transducer, Func <TMedium, TResult> map) => transducer.AsyncCompose(Mapping(map));