code: def _client(self, host, port, unix_socket, auth):
          
          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)
docs: Return a redis client for the configuration.
  
  :param str host: redis host
  :param int port: redis port
  :rtype: redis.Redis