<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def diff(self, items):
 """ Diff the collections with the given items :param items: The items to diff with :type items: mixed :return: A Collection instance :rtype: Collection """

        return self.__class__([i for i in self.items if i not in items])