text: x = np.zeros((10, 10, 4), dtype=np.int8)
  x[:,:,0] = 1
  x[:,:,1] = 2
  x[:,:,2] = 3
  x[:,:,3] = 4
  
  # How to make a (10, 10) structured array with fields 'r', 'g', 'b', 'a',
  # without copying?
  
  y = ...
  
  assert (y['r'] == 1).all()
  assert (y['g'] == 2).all()
  assert (y['b'] == 3).all()
  assert (y['a'] == 4).all()
  