code: def _build_all_reduce_ring(self, core_locations):
      permutation = tpu_util._build_all_reduce_ring(core_locations)
      return [core_locations[element] for element in permutation]
  
imports: from tensorflow.dtensor.python import accelerator_util
  from tensorflow.dtensor.python import layout
  from tensorflow.dtensor.python import numpy_util
  from tensorflow.dtensor.python import tpu_util
  from tensorflow.dtensor.python.tests import test_util
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.ops import math_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 3 for calling the DeviceAssignmentTest obj's underlying member method code with example usage: obj._build_all_reduce_ring(core_locations) and returns: unknown