Hi, It seems that `all_samples` in `full` protocol of the utfvp dataset has a problem and raises an issue. Here is a sample code: ``` from bob.bio.vein.database.utfvp import UtfvpDatabase database = UtfvpDatabase(protocol="full") database.all_samples() ``` and here is the error: ``` packages/bob/bio/base/database/csv_dataset.py", line 494, in all_samples samples = samples + self.background_model_samples() File "..../lib/python3.9/site-packages/bob/bio/base/database/csv_dataset.py", line 381, in background_model_samples self.csv_to_sample_loader.transform(self.train_csv) File "..../lib/python3.9/site-packages/sklearn/pipeline.py", line 635, in transform Xt = transform.transform(Xt) File "..../lib/python3.9/site-packages/bob/pipelines/sample_loaders.py", line 84, in transform X.seek(0) AttributeError: 'NoneType' object has no attribute 'seek' ```