This goes through all the datasets I know about. ::

    for dataset in pluplusch():
        print(dataset)

You can tune it a bit with the parameters. ::

    pluplusch(catalogs = ['http://data.enseignementsup-recherche.gouv.fr'],
              cache_dir = '/lockers/tlevine_vol/dadawarehouse.thomaslevine.com/big/pluplusch')

Add these test cases:

    https://data.cityofnewyork.us, niuh-hrin

If you want to save the data catalog metadata every so often, you might
write a crontab that looks like this.

    @weekly pluplusch --cache-dir ~/$(date --rfc-3339 date)
