def METHOD_NAME() -> None:
    for fp in flightplans:
        elts = fp.decompose()
        assert any(isinstance(p, SpeedLevel) for p in elts)
        # we can parse everything
        assert all(p is not None for p in elts)
        for cur_, next_ in zip(elts, elts[1:]):
            # never two consecutive airways
            assert not isinstance(cur_, Airway) or not isinstance(next_, Airway)
            # never two consecutive navaids (coordinate points are ok though)
            assert not isinstance(cur_, Point) or not isinstance(next_, Point)