Refactor for DefinedNamespace behaviour
@@ -36,7 +36,7 @@ from rdflib.plugins.sparql.sparql import SPARQLError, SPARQLTypeError
# closed namespace, langString isn't in it
-RDF_langString = URIRef(RDF.uri + "langString")
+RDF_langString = str(RDF) + "langString"
def Builtin_IRI(expr, ctx):
