code: def test_load_invalid_mrl():
      # Arrange
      invalid_mrl = "Tests/images/hopper.png"
      mop = ImageMorph.MorphOp()
  
      # Act / Assert
      with pytest.raises(Exception) as e:
          mop.load_lut(invalid_mrl)
      assert str(e.value) == "Wrong size operator file!"
  
imports: import pytest
  from PIL import Image, ImageMorph, _imagingmorph
  from .helper import assert_image_equal_tofile, hopper
label_desc: Use image node_id 21 for calling a global function with example usage: test_load_invalid_mrl() without return types