Python 3 Completion in Vim
First off, the Vim that ships with Ubuntu 14.04 doesn’t support Python 3. Run:
vim --version | grep python
and you get:
-python3
Two ways around it: compile it yourself with the right flags, or just use a ready-made PPA:
sudo apt-add-repository ppa:pi-rho/dev
sudo apt-get update
sudo apt-get install vim
After installing, don’t forget to run that command again and check whether python3 has turned into a plus sign.