<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _client(self, host, port, unix_socket, auth):
 """Return a redis client for the configuration. :param str host: redis host :param int port: redis port :rtype: redis.Redis """

        db = int(self.config['db'])
        timeout = int(self.config['timeout'])
        try:
            cli = redis.Redis(host=host, port=port,
                              db=db, socket_timeout=timeout, password=auth,
                              unix_socket_path=unix_socket)
            cli.ping()
            return cli
        except Exception as ex:
            self.log.error("RedisCollector: failed to connect to %s:%i. %s.",
                           unix_socket or host, port, ex)