python-apt, repositories

[BW <m40636067@gmail.com>]

I'm trying retrieve the related repository of a package-version using
python-apt (I hope it make sense, I don't have the full overview of
the apt system yet).

I'll will use this information to decide which package-version to
download and/or install.

The closest thing I can find about repository in the python-apt
documentation is the package-pinning-with-policy section but it
doesn't seem to provide what I need.
(https://apt-team.pages.debian.net/python-apt/library/apt_pkg.html#package-pinning-with-policy)

How can I retrieve a list of the subscribed repositories, those
registered in /etc/apt/sources.list?
And how can I mape packages to those repositories?

Thanks,
Brian, Denmark