public static IAsyncOptionEnumerable <TResult> SelectMany <TSuccess, TBind, TResult>(this IAsyncOptionEnumerable <TSuccess> source, Func <TSuccess, Option <TBind> > bind, Func <TSuccess, TBind, TResult> resultSelector)
            where TSuccess : notnull
            where TBind : notnull
            where TResult : notnull
        {
            if (bind == null)
            {
                throw new ArgumentNullException(nameof(bind));
            }

            if (resultSelector == null)
            {
                throw new ArgumentNullException(nameof(resultSelector));
            }

            return(source
                   .Select(result => result
                           .Match(success =>
                                  bind
                                  .Invoke(success)
                                  .Map(value => resultSelector.Invoke(success, value)),
                                  Option.None <TResult>
                                  )
                           )
                   .AsAsyncOptionEnumerable());
        }
 public static IAsyncOptionEnumerable <TValue> Where <TValue>(this IAsyncOptionEnumerable <TValue> source, Func <TValue, Option <Unit> > failurePredicate)
 => source
 .Select(value => value
         .Bind(success => failurePredicate
               .Invoke(success)
               .Map(_ => success)
               )
         )
 .AsAsyncOptionEnumerable();
        public static IAsyncOptionEnumerable <TResult> Select <TSuccess, TResult>(this IAsyncOptionEnumerable <TSuccess> source, Func <TSuccess, TResult> selector)
        {
            if (selector == null)
            {
                throw new ArgumentNullException(nameof(selector));
            }

            return(source
                   .Select(result => result
                           .Match(
                               success => Option.Some(selector.Invoke(success)),
                               Option.None <TResult>
                               )
                           )
                   .AsAsyncOptionEnumerable());
        }