use Kubota & done as an option for AGN spectra

[dnarayanan]

https://github.com/arnauqb/qsosed

[RaySSharma]

Looks like most of it is contained within the base class: https://github.com/arnauqb/qsosed/blob/master/qsosed/sed.py Though it does call a few methods from other parts of the package. It doesn't rely on external data though, which makes it easier.