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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def heightmap_lerp_hm( hm1: np.ndarray, hm2: np.ndarray, hm3: np.ndarray, coef: float ) -> None: """Perform linear interpolation between two heightmaps storing the result in ``hm3``. This is the same as doing ``hm3[:] = hm1[:] + (hm2[:] - hm1[:]) * coef`` 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. coef (float):
 The linear interpolation coefficient. """

    lib.TCOD_heightmap_lerp_hm(
        _heightmap_cdata(hm1),
        _heightmap_cdata(hm2),
        _heightmap_cdata(hm3),
        coef,
    )