code: def test_empty_map(env_async):
      tmpl = env_async.from_string('{{ none|map("upper")|list }}')
      assert tmpl.render() == "[]"
  
imports: from collections import namedtuple
  import pytest
  from jinja2 import Environment
  from jinja2.utils import Markup
label_desc: Use image node_id 21 for calling a global function with example usage: test_empty_map(env_async) without return types