code: public DataSet loadFromMetaData(List<RecordMetaData> list) throws IOException {
          if (underlying == null) {
              SequenceRecord r = recordReader.loadSequenceFromMetaData(list.get(0));
              initializeUnderlying(r);
          }
  
          //Two cases: single vs. multiple reader...
          List<RecordMetaData> l = new ArrayList<>(list.size());
          if (singleSequenceReaderMode) {
              for (RecordMetaData m : list) {
                  l.add(new RecordMetaDataComposableMap(Collections.singletonMap(READER_KEY, m)));
              }
          } else {
              for (RecordMetaData m : list) {
                  RecordMetaDataComposable rmdc = (RecordMetaDataComposable) m;
                  Map<String, RecordMetaData> map = new HashMap<>(2);
                  map.put(READER_KEY, rmdc.getMeta()[0]);
                  map.put(READER_KEY_LABEL, rmdc.getMeta()[1]);
                  l.add(new RecordMetaDataComposableMap(map));
              }
          }
  
          return mdsToDataSet(underlying.loadFromMetaData(l));
      }
docs: Load a multiple sequence examples to a DataSet, using the provided RecordMetaData instances.
  
  @param list List of RecordMetaData instances to load from. Should have been produced by the record reader provided
  to the SequenceRecordReaderDataSetIterator constructor
  @return DataSet with the specified examples
  @throws IOException If an error occurs during loading of the data