code: public DataSet loadFromMetaData(List<RecordMetaData> list) throws IOException {
          if (underlying == null) {
              Record r = recordReader.loadFromMetaData(list.get(0));
              initializeUnderlying(r);
          }
  
          //Convert back to composable:
          List<RecordMetaData> l = new ArrayList<>(list.size());
          for (RecordMetaData m : list) {
              l.add(new RecordMetaDataComposableMap(Collections.singletonMap(READER_KEY, m)));
          }
          MultiDataSet m = underlying.loadFromMetaData(l);
  
          return mdsToDataSet(m);
      }
docs: Load a multiple 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 RecordReaderDataSetIterator constructor
  @return DataSet with the specified examples
  @throws IOException If an error occurs during loading of the data