def _load_ontology(self, filename, preview_mode=False):
        """
        Loads an ontology

        Unless preview_mode=True, it is always loaded from the local repository
        note: if the ontology does not have a cached version, it is created

        preview_mode: used to pass a URI/path to be inspected without saving it locally
        """
        if not preview_mode:
            fullpath = self.LOCAL_MODELS + filename
            g = manager.get_pickled_ontology(filename)
            if not g:
                g = manager.do_pickle_ontology(filename)
        else:
            fullpath = filename
            filename = os.path.basename(os.path.normpath(fullpath))
            g = Ontospy(fullpath, verbose=True)
        self.current = {'file': filename, 'fullpath': fullpath, 'graph': g}
        self.currentEntity = None
        self._print_entity_intro(g)
Loads an ontology

        Unless preview_mode=True, it is always loaded from the local repository
        note: if the ontology does not have a cached version, it is created

        preview_mode: used to pass a URI/path to be inspected without saving it locally