code: def test_human_readable():
      """Test human_readable formatter"""
      f = formatters.human_readable
  
      assert f(1) == "1"
      assert f(1.0) == "1"
      assert f(10) == "10"
      assert f(12.5) == "12.5"
      assert f(1000) == "1k"
      assert f(5000) == "5k"
      assert f(100000) == "100k"
      assert f(1253) == "1.253k"
      assert f(1250) == "1.25k"
  
      assert f(0.1) == "100m"
      assert f(0.01) == "10m"
      assert f(0.001) == "1m"
      assert f(0.002) == "2m"
      assert f(0.0025) == "2.5m"
      assert f(0.0001) == "100µ"
      assert f(0.000123) == "123µ"
      assert f(0.00001) == "10µ"
      assert f(0.000001) == "1µ"
      assert f(0.0000001) == "100n"
      assert f(0.0000000001) == "100p"
  
      assert f(0) == "0"
      assert f(0.0) == "0"
      assert f(-1337) == "-1.337k"
      assert f(-0.000000042) == "-42n"
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_human_readable() without return types