as explained in section 2.2 of
https://huggingface.co/papers/2307.01952. Can be used to
simulate an aesthetic score of the generated image by influencing the negative text condition.   Returns 
~pipelines.stable_diffusion_xl.StableDiffusionXLPipelineOutput or tuple
  
~pipelines.stable_diffusion_xl.StableDiffusionXLPipelineOutput if return_dict is True, otherwise a
tuple. When returning a tuple, the first element is a list with the generated im