code: def test_ReSTRenderer_heading():
      r = ReSTRenderer()
  
      template = '{{ "hello" | heading }}'
      assert r.render_string(template, {}) == "hello\n====="
  
      template = '{{ "hello" | heading(1) }}'
      assert r.render_string(template, {}) == "hello\n====="
  
      template = '{{ "русский язык" | heading(2) }}'
      assert r.render_string(template, {}) == (
          "русский язык\n" "------------"
      )
  
      # language: ja
      r.env.language = "ja"
      template = '{{ "русский язык" | heading }}'
      assert r.render_string(template, {}) == (
          "русский язык\n" "======================="
      )
  
label_desc: Use image node_id 2 for calling a global function with example usage: test_ReSTRenderer_heading() without return types