code: def test_scope(self):
      distribution_1 = distribution_lib.Distribution(self.device_mesh)
      distribution_2 = distribution_lib.Distribution(self.device_mesh)
  
      self.assertIsNone(distribution_lib.distribution())
      with distribution_1.scope():
          self.assertIs(distribution_lib.distribution(), distribution_1)
          with distribution_2.scope():
              self.assertIs(
                  distribution_lib.distribution(), distribution_2
              )
  
          self.assertIs(distribution_lib.distribution(), distribution_1)
  
      self.assertIsNone(distribution_lib.distribution())
  
imports: import os
  from unittest import mock
  import numpy
  import pytest
  import tensorflow
  from keras import backend
  from keras import testing
  from keras.backend import distribution_lib
  from keras.distribution import distribution_lib
label_desc: Use image node_id 3 for calling the DistributionTest obj's underlying member method code with example usage: obj.test_scope() without return types