code: def test_l1_loss() -> None:
      loss = imagelosses.SumAbsoluteDifferences(
          reference=124.0 * np.ones((300, 400, 3))
      )
      assert loss(np.ones((300, 400, 3))) == 44280000.0
  
file_path: nevergrad/nevergrad/functions/images/test_imagelosses.py
imports: from pathlib import Path
  import PIL.Image
  import numpy
  import pytest
  from nevergrad.functions.images import imagelosses
label_desc: Use image node_id 2 for calling a global function with example usage: test_l1_loss() without return types