About: http://webisa.webdatacommons.org/403498471

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	So while the argument itself may not be NULL (as it could be if the argument was a pointer), the value that the pointer is pointing to may be NULL, and therefore you will still have to check for NULL pointers.
http://www.w3.org/ns/prov#wasQuotedFrom	stackoverflow.com