Python simulate keydown

After searching for several hours i´m wondering if its possible to simulate a keydown press on the keyboard. For example I want my program to hold the x key down for five seconds so when I run it in notepad it would look like to see something like this: xxxxxxxxxxxxx. I tried around with different pieces of code on the internet, the best thing I could find so far is this:

Key Presses in Python

Is it possible to make it appear to a system that a key was pressed, for example I need to make A key be pressed thousands of times, and it is much to time consuming to do it manually, I would like to write something to do it for me, and the only thing I know well enough is Python.