Extracts template variables from template pages (see http://en.wikipedia.org/wiki/Help:Template#Handling_parameters)
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