code: def delete(self):
          
          MetadataCache.delete(self)
          try:
              self.graph.query('DELETE WHERE { ?s ?p ?o . }')
          except ResultException:
              # this is often just a false positive since Jena Fuseki does not
              # return tuples for a deletion query, so swallowing the exception
              # here is fine
              logging.exception('error when deleting graph')
docs: Deletes the local marker file and also any data in the Fuseki
          server.