def stats(self, key=None):
        """
        Return server stats.

        :param key: Optional if you want status from a key.
        :type key: six.string_types
        :return: A dict with server stats
        :rtype: dict
        """
        # TODO: Stats with key is not working.

        returns = {}
        for server in self.servers:
            returns[server.server] = server.stats(key)

        return returns
Return server stats.

        :param key: Optional if you want status from a key.
        :type key: six.string_types
        :return: A dict with server stats
        :rtype: dict