code: def test_counts(self):
      channel = np.arange(255).reshape(51, 5)
      img = np.empty((51, 5, 3), dtype="uint8")
      img[:, :, 0] = channel
      img[:, :, 1] = channel
      img[:, :, 2] = channel
      r, g, b, v = histograms(img, 255)
      np.testing.assert_array_equal(r, g)
      np.testing.assert_array_equal(r, b)
      np.testing.assert_array_equal(r, v)
      np.testing.assert_array_equal(r, np.ones(255))
  
imports: import numpy
  from skimage.io._plugins._histograms import histograms
label_desc: Use image node_id 2 for calling the TestHistogram obj's underlying member method code with example usage: obj.test_counts() without return types