Create empty split generator

3d-brain-mri.py

@@ -99,7 +99,7 @@ class BrainMRI(datasets.GeneratorBasedBuilder):
         # By default the archives will be extracted and a path to a cached folder where they are extracted is returned instead of the archive
         urls = _URLS[self.config.name]
         data_dir = dl_manager.download_and_extract(urls)
-        return
+        return []
 
     # method parameters are unpacked from `gen_kwargs` as given in `_split_generators`
     def _generate_examples(self, filepath, split):