Kali Users NEED This!!!
This was a pain for me and a good learning curve. You will probably run into a mess of python related errors tryin to install this. Here is my solution:-
update repository manually using nano or watevea delete the lot (or add and clean up later) and paste the following:-
remember to save then do the following :- follow the instructions to download on their page
root@Kali:~# sudo add-apt-repository ppa:kilian/f.lux
root@Kali:~# sudo apt-get update
root@Liak:~# sudo apt-get install fluxgui
Fixed (much faster then it took me;)