def _remove_hstore_virtual_fields(self):
        """ remove hstore virtual fields from class """
        cls = self.model
        # remove all hstore virtual fields related attributes
        if hasattr(cls, '_hstore_virtual_fields'):
            # remove attributes from class
            for field_name in cls._hstore_virtual_fields.keys():
                delattr(cls, field_name)
            delattr(cls, '_hstore_virtual_fields')
        # django >= 1.8
        if parse_version(get_version()[0:3]) < parse_version('1.8'):
            # remove  all hstore virtual fields from meta
            hstore_fields = []
            # get all the existing hstore virtual fields
            for field in getattr(cls._meta, 'virtual_fields'):
                if hasattr(field, 'hstore_field_name'):
                    hstore_fields.append(field)
            # remove from meta
            for field in hstore_fields:
                getattr(cls._meta, 'virtual_fields').remove(field)
            # reset _meta.fields
            fields = [f for f in cls._meta.fields if not hasattr(f, 'hstore_field_name')]
            # cls._meta.fields.__class__ == ImmutableList
            cls._meta.fields = cls._meta.fields.__class__(fields)
        # django <= 1.7
        # TODO: will removed when django 1.7 will be deprecated
        else:
            # remove  all hstore virtual fields from meta
            for meta_fields in ['fields', 'local_fields', 'virtual_fields']:
                hstore_fields = []
                # get all the existing hstore virtual fields
                for field in getattr(cls._meta, meta_fields):
                    if hasattr(field, 'hstore_field_name'):
                        hstore_fields.append(field)
                # remove from meta
                for field in hstore_fields:
                    getattr(cls._meta, meta_fields).remove(field)
dataset/ETHPy150Open djangonauts/django-hstore/django_hstore/fields.py/DictionaryField._remove_hstore_virtual_fields/operator `>=` -> `<`