code: def test_transform(self):
      callback = imaging.ImagingCallback()
      self.assertTrue(callback.transform("test") is "test")
  
      callback = imaging.ImagingCallback(transform=lambda _: "test")
      self.assertTrue(callback.transform("something else") is "test")
  
imports: from unittest import TestCase
  from mock import MagicMock, patch, ANY
  import torch
  import torchbearer
  import torchbearer.callbacks.imaging
  import matplotlib.pyplot
label_desc: Use image node_id 1 for calling the TestImagingCallback obj's underlying member method code with example usage: obj.test_transform() without return types