code: def process_file(self,filename=None, format=None):
          
          rdfgraph = rdflib.Graph()
          if format is None:
              if filename.endswith(".ttl"):
                  format='turtle'
              elif filename.endswith(".rdf"):
                  format='xml'
          rdfgraph.parse(filename, format=format)
          return self.process_rdfgraph(rdfgraph)
docs: Parse a file into an ontology object, using rdflib