distinguish data from ontologies

[ahmad88me]

an enhacement would be to check that the file contains a line like (“.* rdf:type owl:Ontology) (credit to @dachafra).

[ahmad88me]

To look at https://github.com/KnowledgeCaptureAndDiscovery/somef/blob/master/src/somef/extract_ontologies.py (credits to @dgarijo ).