code: def test_vega_output():
      # TODO: use an actual vega spec
      data = pd.DataFrame({"x": [1, 2, 3], "y": [4, 5, 6]})
      obj = Vega(VEGA_SPEC, data)
      js = obj._generate_js(id="ABC")
      assert js != None
  
label_desc: Use image node_id 2 for calling a global function with example usage: test_vega_output() without return types