code: def test_void_caster():
      assert m.load_nullptr_t(None) is None
      assert m.cast_nullptr_t() is None
  
imports: import sys
  import pytest
  import env
  from pybind11_tests import IncType, UserType
  from pybind11_tests import builtin_casters
label_desc: Use image node_id 13 for calling a global function with example usage: test_void_caster() without return types