I've opened the calculator on windows, Windows 8 to be particular I'm using python 3.7.3 and I wanted to close the calculator application so I wrote the following code
os.system('TASKKILL /F /IM calculator.exe')
What weird thing happened is that it didn't give any error but returned '128' and this returned every time.
os.system('TASKKILL /F /IM notepad.exe')
This worked correctly i.e. while closing the notepad application