'Extract the YadisServiceManager for this object\'s URL and
suffix from the session.
@param force: True if the manager should be returned
regardless of whether it\'s a manager for self.url.
@return: The current YadisServiceManager, if it\'s for this
URL, or else None'

def getManager(self, force=False):

    manager = self.session.get(self.getSessionKey())
    if ((manager is not None) and (manager.forURL(self.url) or force)):
        return manager
    else:
        return None
