class_docstr: Sets up distribution strategy for tests.
class_docstr_tok: ["Sets","up","distribution","strategy","for","tests","."]
code: def parameter_modifiers(self):
      return [
          DistributionParameter(),
          combinations_lib.OptionalParameter("use_var_policy"),
      ]
  
imports: import collections
  import copy
  import re
  import sys
  import types
  import unittest
  from absl import app
  import six
  from tensorflow.python.client import session
  from tensorflow.python.distribute import collective_all_reduce_strategy
  from tensorflow.python.distribute import distribute_lib
  from tensorflow.python.distribute import multi_process_runner
  from tensorflow.python.distribute import multi_worker_test_base
  from tensorflow.python.eager import context
  from tensorflow.python.eager import def_function
  from tensorflow.python.framework import combinations
  from tensorflow.python.framework import config
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import test_combinations
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import flags
  from tensorflow.python.platform import tf_logging
  from tensorflow.python.util import tf_decorator
  from tensorflow.python.util import tf_inspect
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 2 for calling the DistributionCombination obj's underlying member method code with example usage: obj.parameter_modifiers() and returns: list