Notes:
should this be "val"^^xsd:dateTime - temp:last_login^^xsd:dateTime

predicates: [lowercase(name),uppercase(name)]
data: John
output: JOHN, john

predicates: ["date(join(":",year,month,day)))", "name"]

foaf:firstName+foaf:surname

"firstname+surname+name"
"predicates" : ["temp1:a","temp1:b","temp1:c"]
["a","b","c"]
["a+b","c"]