def _before_forward(self, **kwargs):
        """
        Concatenate together original and augmented examples.
        """
        assert self.is_training
        super()._before_forward(**kwargs)
        mb_x_augmented = self.augmentations(self.mbatch[0])
        # (batch_size*2, input_size)
        self.mbatch[0] = torch.cat([self.mbatch[0], mb_x_augmented], dim=0)

        Concatenate together original and augmented examples.
        
avalanche/training/supervised/supervised_contrastive_replay.py