message: Fixed typo in usage docstring
  Changed tf.SyncReplicasOptimizer to tf.train.SyncReplicasOptimizer.
diff: @@ -99,7 +99,7 @@ class SyncReplicasOptimizer(optimizer.Optimizer):
  # Note that if you want to have 2 backup replicas, you can change
  # total_num_replicas=52 and make sure this number matches how many physical
  # replicas you started in your job.
  - opt = tf.SyncReplicasOptimizer(opt, replicas_to_aggregate=50,
  + opt = tf.train.SyncReplicasOptimizer(opt, replicas_to_aggregate=50,
  total_num_replicas=50)
  # Some models have startup_delays to help stabilize the model but when using
  