About: http://webisa.webdatacommons.org/150505184

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	If we want to test whether a column is null, we must use the is" operator, not the equality operator.
http://www.w3.org/ns/prov#wasQuotedFrom	slashdot.org