code: def test__not_flat_with_flat_patch(self):
      lr_patch = np.zeros((5, 5, 3))
      with patch(
          "ISR.utils.datahandler.DataHandler._make_img_list",
          return_value=True,
      ):
          with patch(
              "ISR.utils.datahandler.DataHandler._check_dataset",
              return_value=True,
          ):
              DH = DataHandler(
                  lr_dir=None,
                  hr_dir=None,
                  patch_size=0,
                  scale=0,
                  n_validation_samples=None,
              )
      self.assertFalse(DH._not_flat(lr_patch, flatness=0.1))
  
imports: import unittest
  import numpy
  from unittest.mock import patch
  from ISR.utils.datahandler import DataHandler
label_desc: Use image node_id 10 for calling the DataHandlerTest obj's underlying member method code with example usage: obj.test__not_flat_with_flat_patch() without return types