def METHOD_NAME(
    verbose=True, plot=False, warnings=True, debug=False, *args, **kwargs
):
    """Add some slabs in series, ensure that overall transmittance decreases
    Also check that some quantities are propagated (like path length?)
    """
    import matplotlib.pyplot as plt
    from radis.test.utils import getTestFile
    from radis.tools.database import load_spec
    if plot:
        plt.ion()  # dont get stuck with Matplotlib if executing through pytest
    # Get Some spectra
    s = load_spec(getTestFile("CO_Tgas1500K_mole_fraction0.5.spec"), binary=True)
    #    s.update('all')
    assert "transmittance_noslit" not in s.get_vars()
    s_los = SerialSlabs(s, s, s)
    w, T = s_los.get("transmittance_noslit")
    # note that it was calculated despite transmittance not in the initial
    # spectrum
    s.update("transmittance_noslit")  # get from abscoeff
    w1, T1 = s.get("transmittance_noslit")
    # Check it looks alright
    assert (T <= T1).all()
    assert (T != T1).any()
    assert (w == w1).all()
    # because they were the same slabs, intensive conditions should have been propagated
    assert s.conditions["Tgas"] == s_los.conditions["Tgas"]
    # but extensive shouldnt:
    assert s.conditions["path_length"] * 3 == s_los.conditions["path_length"]
    if verbose:
        print("Tested Serialslabs transmittance decreases s1>s2: OK")
    return True