def overrideDiscussionFor(content, allowDiscussion):
    """ Override discussability for the given object or clear the setting.

        o 'allowDiscussion' may be True, False, or None.

        o If 'allowDiscussion' is None, then clear any overridden setting for
          discussability, letting the site's default policy apply.

        o Otherwise, set the override to match 'allowDiscussion'.

        o Permission:  PUblic ????  Should be ManageContent, or something.
        """
