code: @SuppressWarnings("unchecked")
  	public <T> DataSet<T> getDataSet(int id) {
  		return verifyType(id, dataSets.get(id), SetType.DATA_SET);
  	}
docs: Returns the cached {@link DataSet} for the given ID.
  
  @param id  Set ID
  @param <T> DataSet type
  @return Cached DataSet
  @throws IllegalStateException if the cached set is not a DataSet