code: def test_callback_step_output_expr():
      param = ParameterInteger(name="MyInt")
      outputParam1 = CallbackOutput(
          output_name="output1",
          output_type=CallbackOutputTypeEnum.String,
      )
      outputParam2 = CallbackOutput(
          output_name="output2",
          output_type=CallbackOutputTypeEnum.Boolean,
      )
      cb_step = CallbackStep(
          name="MyCallbackStep",
          depends_on=["TestStep"],
          sqs_queue_url="https://sqs.us-east-2.amazonaws.com/123456789012/MyQueue",
          inputs={"arg1": "foo", "arg2": 5, "arg3": param},
          outputs=[outputParam1, outputParam2],
      )
  
      assert cb_step.properties.Outputs["output1"].expr == {
          "Get": "Steps.MyCallbackStep.OutputParameters['output1']"
      }
      assert cb_step.properties.Outputs["output2"].expr == {
          "Get": "Steps.MyCallbackStep.OutputParameters['output2']"
      }
  
file_path: sagemaker-python-sdk/tests/unit/sagemaker/workflow/test_callback_step.py
imports: from __future__ import absolute_import
  import json
  import pytest
  from mock import Mock
  from sagemaker.workflow.parameters import ParameterInteger, ParameterString
  from sagemaker.workflow.pipeline import Pipeline, PipelineGraph
  from sagemaker.workflow.callback_step import CallbackStep, CallbackOutput, CallbackOutputTypeEnum
  from tests.unit.sagemaker.workflow.helpers import CustomStep, ordered
label_desc: Use image node_id 4 for calling a global function with example usage: test_callback_step_output_expr() without return types