code: def test_vec_of_reference_wrapper():
      """#171: Can't return reference wrappers (or STL structures containing them)"""
      assert (
          str(m.return_vec_of_reference_wrapper(UserType(4)))
          == "[UserType(1), UserType(2), UserType(3), UserType(4)]"
      )
  
imports: import pytest
  from pybind11_tests import ConstructorStats, UserType
  from pybind11_tests import stl
label_desc: Use image node_id 16 for calling a global function with example usage: test_vec_of_reference_wrapper() without return types