Creating an alias will not be the best way to do it.
Using update-alternatives
sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.5 1
sudo update-alternatives --install /usr/bin/python python /usr/bin/python2.7 2
sudo update-alternatives --config python Enter 2 for Python 2.7.
By this way, one can select and its set across users and groups.
Use /usr/local/bin/supervisorctl restart all