code: def test_warns_that_it_is_deprecated(self):
      image_fg = np.zeros((1, 1, 3), dtype=np.uint8)
      image_bg = np.copy(image_fg)
      alpha = 1
  
      with warnings.catch_warnings(record=True) as caught_warnings:
          warnings.simplefilter("always")
          _ = overlay.blend_alpha(image_fg, image_bg, alpha)
  
      assert len(caught_warnings) == 1
      assert "imgaug.augmenters.blend.blend_alpha" in str(
          caught_warnings[-1].message
      )
  
imports: from __future__ import print_function, division, absolute_import
  import warnings
  import sys
  import numpy
  import imgaug.augmenters
  import imgaug.augmenters.overlay
label_desc: Use image node_id 1 for calling the Test_blend_alpha obj's underlying member method code with example usage: obj.test_warns_that_it_is_deprecated() without return types