I want to add one more - read the Python source code to the standard library! It's right there in your computer with Python itself.

Years ago, I wrote the following tiny Bash alias to open a Python library in my editor:

openpy () 
{ 
    if [[ -z "$1" ]]; then
        echo "Usage: openpy <module>";
        return 1;
    fi;
    $EDITOR -n `python -c "import $1; print($1.__file__)"`
}

I also use this every day! (If I were writing this today, I’d use $(...) instead of `…`.)