import tensorflow as tf


    best_trial_info_file = os.path.join(FLAGS.output_dir, "best_trial.txt")

    def _best_trial_info():
      """Returns information about which checkpoints have been evaled so far."""
      if tf.gfile.Exists(best_trial_info_file):
        with tf.gfile.GFile(best_trial_info_file, "r") as best_info:
          global_step, best_metric_global_step, metric_value = (
              best_info.read().split(":"))
          global_step = int(global_step)
