Looking for example scripts to learn

I'm trying to learn SikuliX, but the documentation is incredibly hard to understand. I'm trying to get it to simply press Ctrl+A just to practice, but this doesn't seem to work and causes it to type only a literal a:

    
wait(0.5)
keyDown(KEY_CTRL)
wait(0.5)
type('a')
keyUp(KEY_CTRL)

  

Ultimately, I'm trying to figure out how to get it to press Ctrl+Shift+A. Any help would be appreciated!