code: def test_variant(doc):
      assert m.load_variant(1) == "int"
      assert m.load_variant("1") == "std::string"
      assert m.load_variant(1.0) == "double"
      assert m.load_variant(None) == "std::nullptr_t"
  
      assert m.load_variant_2pass(1) == "int"
      assert m.load_variant_2pass(1.0) == "double"
  
      assert m.cast_variant() == (5, "Hello")
  
      assert (
          doc(m.load_variant)
          == "load_variant(arg0: Union[int, str, float, None]) -> str"
      )
  
imports: import pytest
  from pybind11_tests import ConstructorStats, UserType
  from pybind11_tests import stl
label_desc: Use image node_id 14 for calling a global function with example usage: test_variant(doc) without return types