Clear screen in shell

Just a quick question:
How do you clear the screen in shell? I've seen ways like:

    import os

This just opens the windows cmd, clears the screen and closes but I want the shell window to be cleared
(PS: I don't know this helps, but I'm using version 3.3.2 of Python)
Thank you :)

For OS X, you can use subprocess module and call 'cls' from shell:

    import subprocess as sp'cls',shell=True)

To prevent '0' from showing on top of the window, replace the 2nd line with:

    tmp ='cls',shell=True)

For linux, you must replace cls command with clear

    tmp ='clear',shell=True)