code: def test_function_signatures(doc):
      from pybind11_tests import test_callback3, test_callback4
  
      assert (
          doc(test_callback3)
          == "test_callback3(arg0: Callable[[int], int]) -> str"
      )
      assert (
          doc(test_callback4)
          == "test_callback4() -> Callable[[int], int]"
      )
  
imports: import pytest
label_desc: Use image node_id 5 for calling a global function with example usage: test_function_signatures(doc) without return types