When I updated the INDI library, I got a message that Python 3.6 could not be installed, saying:
failed to fetch ppa.launchpad.net/jonathonf/python-3.6/u...6.04.york3_amd64.deb 403 Forbidden [IP: 80].

Is this a problem? And if yes, does anyone know a fix?

I tried to check my version of python, with 'python --version', which gave me 2.7.12
With 'python3 --version' it gave me 3.5.2
So a python 2 and 3 seem to be co-installed. Is that a problem?

Thanks for any insight.