[Zope] why cant i import types ?

Can someone tell me why i cant import types into my python script in CMF? When i put either of the following lines as the first line of my script i get the error that follows from types import * - produces Error Type: ImportError Error Value: "from types import *" is not allowed from types import ListType - produces Error Type: ImportError Error Value: import of "ListType" from "types" is unauthorized. You are not allowed to access ListType in this context