code: def test_as_rgb():
      np.random.seed(2323)
      r = np.random.randint(12, 121, size=(8, 8))
      g = np.random.randint(12, 121, size=(8, 8))
      b = np.random.randint(12, 121, size=(8, 8))
      assert mahotas.as_rgb(r, g, b).max() >= 254
      assert mahotas.as_rgb(r, None, b).shape == (8, 8, 3)
      assert mahotas.as_rgb(r, None, b)[:, :, 1].sum() == 0
  
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 3 for calling a global function with example usage: test_as_rgb() without return types