public static IDataflow <Either <TLeft, IList <TRight> > > BufferSafe <TLeft, TRight>(
this IDataflow <Either <TLeft, TRight> > source, TimeSpan batchTimeout, int count)
{
return(source
.Buffer(batchTimeout, count)
.SelectMany(batch => batch
.GroupBy(item => item.IsRight)
.SelectMany(group => group.Key
? List(
Right <TLeft, IList <TRight> >(
group.Rights().ToList()))
: group
.Lefts()
.Select(Left <TLeft, IList <TRight> >))));
}