code: def up(db, dataset_name):
      match_d = {"name": dataset_name}
      dataset_dict = db.datasets.find_one(match_d)
  
      if "runs" not in dataset_dict:
          dataset_dict["runs"] = {}
  
      app_config = dataset_dict.get("app_config", None)
      if app_config is not None:
          color_scheme = app_config.get("color_scheme", None)
          if color_scheme is not None:
              # Generate new ID only if color_scheme exists
              color_scheme["_id"] = ObjectId()
              # Initialize new fields with default values
              color_scheme["color_by"] = color_scheme.get(
                  "color_by", "field"
              )
              color_scheme["colorscales"] = color_scheme.get(
                  "colorscales", []
              )
              color_scheme[
                  "default_mask_targets_colors"
              ] = color_scheme.get("default_mask_targets_colors", [])
              color_scheme["default_colorscale"] = color_scheme.get(
                  "default_colorscale",
                  {"name": "viridis", "list": None},
              )
              color_scheme["label_tags"] = color_scheme.get(
                  "label_tags", {"fieldColor": None, "valueColors": []}
              )
              color_scheme["multicolor_keypoints"] = color_scheme.get(
                  "multicolor_keypoints", False
              )
              color_scheme["opacity"] = color_scheme.get("opacity", 0.7)
              color_scheme["show_skeletons"] = color_scheme.get(
                  "show_skeletons", True
              )
  
              # Handle nested fields within 'fields'
              fields = color_scheme.get("fields", [])
              if fields:
                  for field in fields:
                      if field is not None:
                          field.setdefault("maskTargetsColors", [])
  
      db.datasets.replace_one(match_d, dataset_dict)
  
label_desc: Use image node_id 1 for calling a global function with example usage: up(db, dataset_name) without return types