def token_drop(self, labels, force_drop_ids=None):
        """
        Drops labels to enable classifier-free guidance.
        """
        if force_drop_ids is None:
            drop_ids = torch.rand(labels.shape[0], device=labels.device) < self.dropout_prob
        else:
            drop_ids = torch.tensor(force_drop_ids == 1)
        labels = torch.where(drop_ids, self.num_classes, labels)
        return labels

        Drops labels to enable classifier-free guidance.
        
src/diffusers/models/embeddings.py