#Running pip or pip3 directly is no longer recommended, in favor of:
python3 -m pip install whatever
#This guarantees that you're absolutely positively running the pip 
#that goes with whatever python3 means, while pip3 just means you're running the pip that goes with some Python 3.x, which may be any of the various ones you've installed.
#Or, even better, use virtual environments, 
#so you can rely on the fact that python and pip are 
#the commands from the currently-active environment, 
#and not even worry about what they mean system-wide.