code: def test_supervised_outputs_none(self):
      outputter = MockSupervisedOutput(
          constant_op.constant([0]), None, None
      )
      self.assertLen(outputter.loss, 1)
      self.assertIsNone(outputter.predictions)
      self.assertIsNone(outputter.metrics)
  
imports: from tensorflow.core.framework import tensor_shape_pb2
  from tensorflow.core.framework import types_pb2
  from tensorflow.core.protobuf import meta_graph_pb2
  from tensorflow.python.eager import context
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import sparse_tensor
  from tensorflow.python.framework import tensor
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import control_flow_ops
  from tensorflow.python.ops import metrics
  from tensorflow.python.ops import variables
  from tensorflow.python.platform import test
  from tensorflow.python.saved_model import signature_constants
  from tensorflow.python.saved_model.model_utils import export_output
label_desc: Use image node_id 2 for calling the SupervisedOutputTest obj's underlying member method code with example usage: obj.test_supervised_outputs_none() without return types