if a task has any notify elements, flag handlers for run
        at end of execution cycle for hosts that have indicated
        changes have been made

def _flag_handler(self, play, handler_name, host):
        '''
        if a task has any notify elements, flag handlers for run
        at end of execution cycle for hosts that have indicated
        changes have been made
        '''

        found = False
        for x in play.handlers():
            if handler_name == utils.template(play.basedir, x.name, x.module_vars):
                found = True
                self.callbacks.on_notify(host, x.name)
                x.notified_by.append(host)
        if not found:
            raise errors.AnsibleError("change handler (%s) is not defined" % handler_name)