code: def test_to_string():
      prop = Properties(
          "MyStep", shape_name="DescribeTrainingJobResponse"
      )
  
      assert prop.CreationTime.to_string().expr == {
          "Std:Join": {
              "On": "",
              "Values": [{"Get": "Steps.MyStep.CreationTime"}],
          },
      }
  
file_path: sagemaker-python-sdk/tests/unit/sagemaker/workflow/test_properties.py
imports: from __future__ import absolute_import
  import pytest
  from mock import Mock
  from copy import deepcopy
  from sagemaker.workflow.properties import Properties
  from sagemaker.workflow.step_outputs import get_step
label_desc: Use image node_id 7 for calling a global function with example usage: test_to_string() without return types