addressing ocmments

official/vision/beta/projects/yolo/optimization/sgd_torch.py

 from tensorflow.python.framework import ops
 from tensorflow.python.ops import array_ops
 from tensorflow.keras.optimizers.schedules import LearningRateSchedule
-from tensorflow.python.training import gen_training_ops
 
 import tensorflow as tf
 import re
 import logging
 
-try:
-  from keras.optimizer_v2.optimizer_v2 import _var_key
-except:
-  def _var_key(var):
+
+def _var_key(var):
   """Key for representing a primary variable, for looking up slots.
   In graph mode the name is derived from the var shared name.
   In eager mode the name is derived from the var unique id.