code: def down(db, dataset_name):
      match_d = {"name": dataset_name}
      dataset_dict = db.datasets.find_one(match_d)
  
      evaluations = dataset_dict.get("evaluations", {})
      for eval_doc in evaluations.values():
          eval_doc["eval_key"] = eval_doc.pop("key")
          eval_doc.pop("timestamp")
          eval_doc["pred_field"] = eval_doc["config"].pop("pred_field")
          eval_doc["gt_field"] = eval_doc["config"].pop("gt_field")
  
      dataset_dict["evaluations"] = evaluations
  
      dataset_dict.pop("brain_methods", None)
      db.datasets.replace_one(match_d, dataset_dict)
  
label_desc: Use image node_id 2 for calling a global function with example usage: down(db, dataset_name) without return types