When I was first starting out my programming adventures with Python, someone told me that I should work with Python 3 instead of 2 because that's what will be maintained in the future (this was some 8 years ago). I decided to listen and when I got home I opened up my terminal, wrote:

sudo apt-get remove python

Followed by

sudo apt-get install python3

Only to be suddenly greeted with:

sudo: command not found