sentinel.go
func (s *Sentinel) MasterAddr() (string, error) {
	res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
		return queryForMaster(c, s.MasterName)
	})
	if err != nil {
		return "", err
	}
	return res.(string), nil
}
func (s *Sentinel) MasterAddr() (string, error) {
	res, err := s.doUntilSuccess(func(c redis.Conn) (interface{}, error) {
		return queryForMaster(c, s.MasterName)
	})
	if err != nil {
		return "", err
	}
	return res.(string), nil
}
// MasterAddr returns an address of current Redis master instance.