code: def test_constant_dunder_to_string(env):
      t = env.from_string("{{ true.__class__|string }}")
      result = t.render()
      assert not isinstance(result, type)
      assert result in {"<type 'bool'>", "<class 'bool'>"}
  
imports: import pytest
  from jinja2._compat import text_type
  from jinja2.exceptions import UndefinedError
  from jinja2.nativetypes import NativeEnvironment
  from jinja2.nativetypes import NativeTemplate
  from jinja2.runtime import Undefined
label_desc: Use image node_id 14 for calling a global function with example usage: test_constant_dunder_to_string(env) without return types