Extracts page ids of articles, e.g.
<http://dbpedia.org/resource/Foo> <http://dbpedia.org/ontology/wikiPageID> "123456"^^<xsd:integer> .
Datasets generated by this extractor.
Datasets generated by this extractor. Used for serialization. If a mapping implementation
does not return all datasets it produces, serialization may fail.
The subject URI of the generated triples
A graph holding the extracted data
when extractor needs some finalization
when extractor has a pre-phase