code: def _get_cand_values(candidate, key_table):
      
      # NOTE: Import just before checking to avoid circular imports.
      from fonduer.features.models import FeatureKey
      from fonduer.supervision.models import GoldLabelKey, LabelKey
  
      if key_table == FeatureKey:
          return candidate.features
      elif key_table == LabelKey:
          return candidate.labels
      elif key_table == GoldLabelKey:
          return candidate.gold_labels
      else:
          raise ValueError(f"{key_table} is not a valid key table.")
docs: Get the corresponding values for the key_table.