def _filter(self) -> None:
        """Filter CIFAR dataset: select images of 0, 1, 2, 3, 4 classes."""
        mask = np.array(self.targets) < self._split
        self.data = self.data[mask]
        self.targets = np.array(self.targets)[mask].tolist()
Filter CIFAR dataset: select images of 0, 1, 2, 3, 4 classes.
catalyst/contrib/datasets/cifar.py