code: def test_stretch_rgb():
      r = np.arange(256).reshape((32, -1))
      g = 255 - r
      b = r / 2
      s = mh.stretch(np.dstack([r, g, b]))
      s_rgb = mh.stretch_rgb(np.dstack([r, g, b]))
      assert not np.all(s == s_rgb)
      assert np.all(s[:, :, 0] == s_rgb[:, :, 0])
      assert np.all(mh.stretch(b) == mh.stretch_rgb(b))
  
file_path: mahotas/mahotas/tests/test_stretch.py
imports: from mahotas.stretch import stretch
  import mahotas
  import mahotas
  import pytest
  import numpy
label_desc: Use image node_id 7 for calling a global function with example usage: test_stretch_rgb() without return types