def _metric_fn(x):
   labels = x["labels"]
   predictions = x["predictions"]
   return metrics.true_negatives_at_thresholds(labels, predictions, [.5])
 def _metric_fn(x):
     labels = x["labels"]
     predictions = x["predictions"]
     return metrics.true_negatives_at_thresholds(
         labels, predictions, [.5])