library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)  __call__  < source > ( prompt: Union = None height: int = 512 width: int = 512 prior_num_inference_steps: int = 60 prior_timesteps: Optional = None prior_guidance_scale: float = 4.0 num_inference_steps: int = 12 decoder_timesteps: Optional = None decoder_guidance_scale: float = 0.0 negative_prompt: Union = None prompt_embeds: Optional = None negative_prompt_embeds: Optional = None num_images_per_prompt: int = 1 generator: Union = None latents: Optional = None output_type: Optional = 'pil' return_dict: bool = True prior_callback_on_step_end: Optional = None prior_callback_on_step_end_tensor_inputs: List = ['latents'] callback_on_step_end: Optional = None callback_on_step_end_tensor_inputs: List = ['latents'] **kwargs  )   Parameters   prompt (str or List[str]) —