code: def check_and_correct(self, cfg):
      def _check_helper(loss_cfg, dataset_ignore_index):
          if "ignore_index" not in loss_cfg:
              loss_cfg["ignore_index"] = dataset_ignore_index
          else:
              assert loss_cfg["ignore_index"] == dataset_ignore_index, (
                  "the ignore_index in loss and train_dataset must be the same. Currently, loss ignore_index = {}, "
                  "train_dataset ignore_index = {}".format(
                      loss_cfg["ignore_index"], dataset_ignore_index
                  )
              )
  
      loss_cfg = cfg.dic.get(self.loss_name, None)
      if loss_cfg is None:
          return
  
      train_dataset_cfg = cfg.train_dataset_cfg
      val_dataset_cfg = cfg.val_dataset_cfg
      assert (
          train_dataset_cfg != {}
      ), "No train_dataset specified in the configuration file."
      if train_dataset_cfg["type"] != "Dataset":
          return
      if val_dataset_cfg != {}:
          assert (
              val_dataset_cfg["type"] == "Dataset"
          ), "The type of train_dataset and val_dataset must be the same"
  
      value_set = set()
      value_name = "ignore_index"
      if value_name in train_dataset_cfg:
          value_set.add(train_dataset_cfg[value_name])
      if value_name in val_dataset_cfg:
          value_set.add(val_dataset_cfg[value_name])
  
      if len(value_set) > 1:
          raise ValueError(
              "`ignore_index` is not consistent: {}. Please set "
              "it consistently in train_dataset and val_dataset".format(
                  value_set
              )
          )
      if len(value_set) == 1:
          ignore_index = value_set.pop()
          for loss_cfg_i in loss_cfg["types"]:
              if loss_cfg_i["type"] == "MixedLoss":
                  for loss_cfg_j in loss_cfg_i["losses"]:
                      _check_helper(loss_cfg_j, ignore_index)
              else:
                  _check_helper(loss_cfg_i, ignore_index)
  
imports: import copy
  from paddleseg.utils import logger
  from paddleseg.utils import utils
label_desc: Use image node_id 2 for calling the DefaultSyncIgnoreIndexRule obj's underlying member method code with example usage: obj.check_and_correct(cfg) without return types