code: private static void setStorageEngine(Dataframe dataset) {
          //create a single storage engine for all the MapRealMatrixes
          if (storageEngine == null) {
              synchronized(DataframeMatrix.class) {
                  if (storageEngine == null) {
                      String storageName = "mdf" + RandomGenerator.getThreadLocalRandomUnseeded().nextLong();
                      storageEngine = dataset.configuration.getStorageConfiguration().createStorageEngine(storageName);
                  }
              }
          }
      }
docs: Initializes the static storage engine if it's not already set.
  
  @param dataset