Answers for "ubuntu 16.04 upgrade python 3.5 to 3.7"

install python 3.6 ubuntu 16.04

$ sudo add-apt-repository ppa:deadsnakes/ppa
$ sudo apt update
$ sudo apt install python3.6

how to upgrade python from 2.7 to 2.9 on ubuntu 14.04

git clone https://github.com/pyenv/pyenv.git ~/.pyenv
 git clone https://github.com/pyenv/pyenv-virtualenv.git ~/.pyenv/plugins/pyenv-virtualenv