code: def testIsCustomDevice(self):
      device_name = "/job:localhost/replica:0/task:0/device:CUSTOM:0"
      (
          device,
          device_info,
          _,
          _,
      ) = custom_device_testutil.GetLoggingDeviceCapsules(device_name)
      context.register_custom_device(device, device_name, device_info)
  
      self.assertTrue(context.is_custom_device(device_name))
      self.assertFalse(context.is_custom_device("cpu:0"))
  
file_path: tensorflow/tensorflow/python/eager/custom_device_test.py
imports: from tensorflow.python.eager import context
  from tensorflow.python.eager import custom_device_testutil
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 3 for calling the CustomDeviceTest obj's underlying member method code with example usage: obj.testIsCustomDevice() without return types