def METHOD_NAME():
    xs_cache["E_g"] = np.array([3, 2, 1.0])
    chanfunc = lambda nuc: np.array([1.0, nuc], float)
    # Test dict
    nucspec = {1: 1, 10: 2}
    obs = _atom_mass_channel(chanfunc, nucspec)
    exp = np.array([1.0, 7.0])
    assert_array_equal(obs, exp)
    # Test list of tuples
    nucspec = [(1, 1), (10, 2)]
    obs = _atom_mass_channel(chanfunc, nucspec)
    exp = np.array([1.0, 7.0])
    assert_array_equal(obs, exp)
    # test material
    h2o = Material({10010000: 0.11191487328888054, 80160000: 0.8880851267111195})
    obs = _atom_mass_channel(chanfunc, h2o)
    exp = np.array([1.0, 33393333.333333336])
    assert_array_almost_equal(obs, exp)