code: def test_flatten_channels_first(self):
      self._core_flatten(
          batch_input_shape=[4, 5, 2, 2], data_format="channels_first"
      )
  
file_path: tf-encrypted/tf_encrypted/keras/layers/flatten_test.py
imports: import unittest
  import numpy
  import pytest
  import tf_encrypted
  from tf_encrypted.keras.testing_utils import agreement_test
label_desc: Use image node_id 3 for calling the TestFlatten obj's underlying member method code with example usage: obj.test_flatten_channels_first() without return types