 2D Transformer model for image-like data.  forward  < source > ( hidden_states: Tensor encoder_hidden_states: Optional = None timestep: Optional = None added_cond_kwargs: Dict = None class_labels: Optional = None cross_attention_kwargs: Dict = None attention_mask: Optional = None encoder_attention_mask: Optional = None return_dict: bool = True  )   Parameters   hidden_states (torch.LongTensor of shape (batch size, num latent pixels) if discret