l class labels for conditioning. Their embeddings will be summed with the timestep embeddings.   timestep_cond (torch.Tensor, optional, defaults to None) —
Additional conditional embeddings for timestep. If provided, the embeddings will be summed with the
timestep_embedding passed through the self.time_embedding layer to obtain the final timestep
embeddings.   attention_mask (torch.Tensor, optional, defaults to None) —
An attention mask of shap