How does Spectrum1D report rest-frame Fnu and flambda?

How does specutils.Spectrum1D() return the rest-frame fnu or flambda? While I see the redshift attribute of Spectrum1D, I can't find where the documentation explains how to apply it to the flux, to correct for (1+z) -- the effect commonly known as "bandwidth compression" for flux density (fnu). In other words, dividing by (1+z) to go from observed fnu to rest fnu, and multiplying by (1+z) to go from observed f_lambda to rest f_lambda. It's so easy to lose track of a 1+z, and it really matters. A use case would be to plot observed wave, observed fnu, and then plot rest wave, rest_fnu, where the rest_fnu should be lower by (1+z).

Here's how I do the conversions in my own code:
https://github.com/janerigby/jrr/blob/master/spec.py look at convert2restframe_df()

Start by reviewing specutils.Spectrum1D's redshift attribute and the linked spec.py convert2restframe_df() example. Document how observed fnu and flambda are converted to rest-frame values, including the (1+z) factors, and show the observed-versus-rest plotting use case. Done means the behavior and conversions are clear in the project documentation.

Written by the indexing model from the issue text.