code: def test_lines():
      p = (
          ggplot(data, aes(x="x", y="y"))
          + geom_point(alpha=0.5)
          + geom_quantile(
              quantiles=[0.001, 0.5, 0.999], formula="y~x", size=2
          )
      )
  
      # Two (.001, .999) quantile lines should bound the points
      # from below and from above, and the .5 line should go
      # through middle (approximately).
      assert p == "lines"
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_lines() without return types