code: def test_lighten():
      """Test lighten color function"""
      assert lighten("#800", 20) == "#e00"
      assert lighten("#800", 0) == "#800"
      assert lighten("#ffffff", 10) == "#ffffff"
      assert lighten("#000000", 10) == "#1a1a1a"
      assert lighten("#f3148a", 25) == "#f98dc6"
      assert lighten("#121212", 1) == "#151515"
      assert lighten("#999999", 100) == "#ffffff"
      assert lighten("#1479ac", 8) == "#1893d1"
  
imports: from __future__ import division
  from pygal.colors import darken, desaturate, hsl_to_rgb, lighten, parse_color, rgb_to_hsl, rotate, saturate, unparse_color
label_desc: Use image node_id 4 for calling a global function with example usage: test_lighten() without return types