code: def test_no_fill():
      p = (
          ggplot(data, aes("x", group="factor(z)"))
          + geom_polygon(aes(y="y"), fill=None, color="red", size=2)
          + geom_polygon(
              aes(y="y+2"), fill="None", color="green", size=2
          )
          + geom_polygon(
              aes(y="y+4"), fill="none", color="blue", size=2
          )
      )
      assert p == "no_fill"
  
label_desc: Use image node_id 2 for calling a global function with example usage: test_no_fill() without return types