code: public static <E> View<E> viewForUri(Dataset<E> dataset, URI uri) {
      if (dataset instanceof FileSystemDataset) {
        return ((FileSystemDataset<E>) dataset).viewForUri(uri);
      }
      throw new IllegalArgumentException("Not a file system dataset: " + dataset);
    }
docs: Convert a URI for a partition directory in a filesystem dataset to a {@link View}
  object representing that partition.
  @param dataset the (partitioned) filesystem dataset
  @param uri the path to the partition directory
  @return a view of the partition