code: def heightmap_add_hm(
      hm1: np.ndarray, hm2: np.ndarray, hm3: np.ndarray
  ) -> None:
      
      hm3[:] = hm1[:] + hm2[:]
docs: Add two heightmaps together and stores the result in ``hm3``.
  
      Args:
          hm1 (numpy.ndarray): The first heightmap.
          hm2 (numpy.ndarray): The second heightmap to add to the first.
          hm3 (numpy.ndarray): A destination heightmap to store the result.
  
      .. deprecated:: 2.0
          Do ``hm3[:] = hm1[:] + hm2[:]`` instead.