code: def test_display_compositor_definition(self):
      definition = " display factory(Image * Image * Image) RGBTEST"
      self.line_magic("compositor", definition)
  
      compositors = [
          c for c in Compositor.definitions if c.group == "RGBTEST"
      ]
      self.assertEqual(len(compositors), 1)
      self.assertEqual(compositors[0].group, "RGBTEST")
      self.assertEqual(compositors[0].mode, "display")
  
imports: from unittest import SkipTest
  import holoviews
  from holoviews.core.options import Store
  from pyviz_comms import CommManager
  from holoviews.operation import Compositor
label_desc: Use image node_id 3 for calling the TestCompositorMagic obj's underlying member method code with example usage: obj.test_display_compositor_definition() without return types