implemented for all pipelines (downloading, saving, running on a particular device, etc.).  __call__  < source > ( prompt: Union = None num_images_per_prompt: int = 1 prior_num_inference_steps: int = 25 decoder_num_inference_steps: int = 25 super_res_num_inference_steps: int = 7 generator: Union = None prior_latents: Optional = None decoder_latents: Optional = None super_res_latents: Optional = None text_model_output: Union = None text_attention_mask: Optional = None prior_guidance_scale: float = 4.0 decoder_guidance_scale: float = 8.0 output_type: Optional = 'pil' return_dict: bool = True  ) → ImagePipelineOutput or tuple  Parameters   prompt (str or List[str]) —