Unable to set default python version to python3 in ubuntu

Question

I was trying to set default python version to python3 in Ubuntu 16.04. By default it is python2 (2.7). I followed below steps :

Answer 1

As it says, update-alternatives --install needs and arguments.

You have link (/usr/bin/python), name (python), and path (/usr/bin/python3), you're missing priority.

update-alternatives --help says:

is an integer; options with higher numbers have higher priority in automatic mode.

So just put a 100 or something at the end