code: def ui(self, is_img2img):
      with InputAccordion(
          False, label="Refiner", elem_id=self.elem_id("enable")
      ) as enable_refiner:
          with gr.Row():
              refiner_checkpoint = gr.Dropdown(
                  label="Checkpoint",
                  elem_id=self.elem_id("checkpoint"),
                  choices=sd_models.checkpoint_tiles(),
                  value="",
                  tooltip="switch to another model in the middle of generation",
              )
              create_refresh_button(
                  refiner_checkpoint,
                  sd_models.list_models,
                  lambda: {"choices": sd_models.checkpoint_tiles()},
                  self.elem_id("checkpoint_refresh"),
              )
  
              refiner_switch_at = gr.Slider(
                  value=0.8,
                  label="Switch at",
                  minimum=0.01,
                  maximum=1.0,
                  step=0.01,
                  elem_id=self.elem_id("switch_at"),
                  tooltip="fraction of sampling steps when the switch to refiner model should happen; 1=never, 0.5=switch in the middle of generation",
              )
  
      def lookup_checkpoint(title):
          info = sd_models.get_closet_checkpoint_match(title)
          return None if info is None else info.title
  
      self.infotext_fields = [
          (enable_refiner, lambda d: "Refiner" in d),
          (
              refiner_checkpoint,
              lambda d: lookup_checkpoint(d.get("Refiner")),
          ),
          (refiner_switch_at, "Refiner switch at"),
      ]
  
      return enable_refiner, refiner_checkpoint, refiner_switch_at
  
file_path: stable-diffusion-webui/modules/processing_scripts/refiner.py
imports: import gradio
  from modules import scripts, sd_models
  from modules.ui_common import create_refresh_button
  from modules.ui_components import InputAccordion
label_desc: Use image node_id 4 for calling the ScriptRefiner obj's underlying member method code with example usage: obj.ui(is_img2img) and returns: enable_refiner,  refiner_checkpoint,  refiner_switch_at, unknown