def METHOD_NAME(model):
    assert len(model.megacomplex) == 3
    for i in range(1, 3):
        label = f"cmplx{i}"
        assert label in model.megacomplex
        megacomplex = model.megacomplex[label]
        assert isinstance(megacomplex, DecayMegacomplex)
        assert megacomplex.label == label
        assert megacomplex.k_matrix == [f"km{i}"]
    assert "cmplx3" in model.megacomplex
    megacomplex = model.megacomplex["cmplx3"]
    assert len(megacomplex.shape) == 2
    assert megacomplex.shape["s1"] == "shape1"
    assert megacomplex.shape["s2"] == "shape2"