code: def test_custom_async_filter(env_async):
      async def customfilter(val):
          return str(val)
  
      env_async.filters["customfilter"] = customfilter
      tmpl = env_async.from_string(
          "{{ 'static'|customfilter }} {{ arg|customfilter }}"
      )
      out = tmpl.render(arg="dynamic")
      assert out == "static dynamic"
  
imports: from collections import namedtuple
  import pytest
  from markupsafe import Markup
  from jinja2 import Environment
  from jinja2.async_utils import auto_aiter
label_desc: Use image node_id 28 for calling a global function with example usage: test_custom_async_filter(env_async) and returns: str