About: http://webisa.webdatacommons.org/415110282

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Having an old property set to null is a common scenario in a schemaless datastore like the gae-datastore.
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com