processed method Null safety
Get a chunk of processed data.
When there are no more data available, processed will return null.
Set flush to false for non-final calls
to improve performance of some filters.
The last call to processed should have end set to true. This will
make sure an 'end' packet is written on the stream.
Implementation
// TODO: Which stream?
List<int>? processed({bool flush = true, bool end = false});