code: def test_add_func():
      var_start_datetime = ExecutionVariables.START_DATETIME
      var_current_datetime = ExecutionVariables.CURRENT_DATETIME
  
      with pytest.raises(TypeError) as error:
          var_start_datetime + var_current_datetime
  
      assert (
          str(error.value)
          == "Pipeline variables do not support concatenation."
      )
  
imports: from __future__ import absolute_import
  import pytest
  from sagemaker.workflow.execution_variables import ExecutionVariables
label_desc: Use image node_id 4 for calling a global function with example usage: test_add_func() without return types