isbn.py should be enhanced so that on a Wikibase site it selects (detects?) the ISBN10 and ISBN13 properties (e.g. on Wikidata, http://wikidata.org/wiki/Special:search/property:isbn ), and performs data validation / cleansing on the Wikibase items with that property.
http://www.google-melange.com/gci/task/view/google/gci2014/5832533526708224