def METHOD_NAME(wl, fnu, dfnu, wave_units, flux_units):
    """
    Combine lists of 1D spectra into a composite `~specutils.Spectrum1D` object.
    Parameters
    ----------
    wl : list of `~astropy.units.Quantity`s
        Wavelength in each spectral channel
    fnu : list of `~astropy.units.Quantity`s
        Flux in each spectral channel
    dfnu : list of `~astropy.units.Quantity`s
        Uncertainty on each flux
    Returns
    -------
    spec : `~specutils.Spectrum1D`
        Composite 1D spectrum.
    """
    wlallarr = np.array(wl)
    fnuallarr = np.array(fnu)
    dfnuallarr = np.array(dfnu)
    srtind = np.argsort(wlallarr)
    wlall = wlallarr[srtind]
    fnuall = fnuallarr[srtind]
    fnuallerr = dfnuallarr[srtind]
    # units are not being handled properly yet.
    unc = StdDevUncertainty(fnuallerr * flux_units)
    spec = Spectrum1D(flux=fnuall * flux_units, spectral_axis=wlall * wave_units,
                      uncertainty=unc)
    return spec