code: def test_prepare_video(self):
      # at each timestep the sum over all other dimensions of the video should stay the same
      np.random.seed(1)
      V_before = np.random.random((4, 10, 3, 20, 20))
      V_after = _prepare_video(np.copy(V_before))
      V_before = np.swapaxes(V_before, 0, 1)
      V_before = np.reshape(V_before, newshape=(10, -1))
      V_after = np.reshape(V_after, newshape=(10, -1))
      np.testing.assert_array_almost_equal(
          np.sum(V_before, axis=1), np.sum(V_after, axis=1)
      )
  
file_path: tensorboardX/tests/test_utils.py
imports: from tensorboardX import summary
  from tensorboardX.utils import make_grid, _prepare_video, convert_to_HWC
  import numpy
  import pytest
  import unittest
label_desc: Use image node_id 2 for calling the UtilsTest obj's underlying member method code with example usage: obj.test_prepare_video() without return types