code: def combine_metric_fns(metric_fn_list):
      """Returns a single metric_fn that combines the outputs of metric_fn_list.
  
      Args:
        metric_fn_list: A list of functions that each takes arguments `labels` and
          `predictions` and returns a dictionary mapping string keys to (tensor,
          update_op) tuples.
  
      Returns:
        A dictionary mapping string keys to (tensor, update_op) tuples.
      """
  
      def _metric_fn(labels, predictions, weights=None):
          """Returns a dictionary mapping string to (tensor, update_op) tuples."""
  
          metrics_dict = {}
          for child_metric_fn in metric_fn_list:
              metrics_dict.update(
                  child_metric_fn(labels, predictions, weights)
              )
          return metrics_dict
  
      return _metric_fn
  
imports: from absl import logging
  import tensorflow.compat.v2
label_desc: Use image node_id 6 for calling a global function with example usage: combine_metric_fns(metric_fn_list) and returns: _metric_fn, metrics_dict