class_docstr: Base class of solver.
class_docstr_tok: ["Base","class","of","solver","."]
docstr: make var average ema 
docstr_tok: ["make","var","average","ema"]
code: def get_var_avg_ema(self, decay, global_step=None):
      """make var average ema"""
      return tf.train.ExponentialMovingAverage(
          decay, global_step or tf.train.get_or_create_global_step()
      )
  
imports: import abc
  import math
  import delta.compat
  import tensorflow_addons
  from absl import logging
  from delta import utils
  from delta.utils import optimizer
  from delta.utils.register import registers
label_desc: Use image node_id 11 for calling the Solver obj's underlying member method code with example usage: obj.get_var_avg_ema(decay, global_step) and returns: tf