code: def testOptimizeLayoutUnsplittable(self):
      x1 = mtf.zeros(self.mesh, "a:10,b:5")
      x2 = mtf.zeros(self.mesh, "b:5,c:20")
      mtf.UnstackOperation(x1, mtf.Dimension("a", 10))
      mtf.UnstackOperation(x2, mtf.Dimension("c", 20))
      optimizer = self.get_layout_optimizer()
  
      # No dimensions can be split, because a and c are unstack dimensions and
      # b has size 5 (so there are divisiblity issues).
      self.assertEqual(optimizer.solve(), "")
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import mesh_tensorflow
  from mesh_tensorflow.auto_mtf import layout_optimizer
  from mesh_tensorflow.auto_mtf import memory_estimator
  import six
  import tensorflow.compat.v1
label_desc: Use image node_id 5 for calling the OptimizeLayoutTest obj's underlying member method code with example usage: obj.testOptimizeLayoutUnsplittable() without return types