def append(self, key, value=None, dir=False, ttl=None, timeout=None):
        """Requests to create an ordered node into a node by the given key."""
        url = self.make_key_url(key)
        data = self.build_args({
            'value': (six.text_type, value),
            'dir': (bool, dir or None),
            'ttl': (int, ttl),
        })
        try:
            res = self.session.post(url, data=data, timeout=timeout)
        except:
            self.erred()
        return self.wrap_response(res)