Install PyAutoGUI

On Windows, this is

C:\Python34\pip.exe install pyautogui

(Though you may have a different version of Python installed other than 3.4)

On OS X, this is

pip3 install pyobjc-framework-Quartz
pip3 install pyobjc-core
pip3 install pyobjc
pip3 install pyautogui

If you are running El Capitan and have problems installing pyobjc try:

MACOSX_DEPLOYMENT_TARGET=10.11 pip install pyobjc

On Linux, this is

pip3 install python3-xlib
sudo apt-get install scrot
sudo apt-get install python3-tk
sudo apt-get install python3-dev
pip3 install pyautogui