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