In the sense that instead of PartitionedDataSet searching every file in the directory of a certain suffix, it searches a list of pre-determined filenames. If the load method finds the specified list of filenames, it loads it, just like PartitionedDataSet. If there are files missing, it can return empty or raise an error.
I tried overloading the
method of PartitionedDataSet but I think there should be a better way