You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: bsrelation.go
    path of file: ./repos/bk-cmdb/src/source_controller/cacheservice/event/bsrelation
    
    the code of the file until where you have to start completion: /*
 * Tencent is pleased to support the open source community by making 蓝鲸 available.
 * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
 * Licensed under the MIT License (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License 
    
func NewBizSetRelation(watch stream.LoopInterface, watchDB *local.Mongo, ccDB dal.DB) error {
	base := mixevent.MixEventFlowOptions{
		MixKey:       event.BizSetRelationKey,
		Watch:        watch,
		WatchDB:      watchDB,
		CcDB:         ccDB,
		EventLockKey: bizSetRelationLockKey,
		EventLockTTL: bizSetRelationLockTTL,
	}

	// watch biz set event
	bizSet := base
	bizSet.Key = event.BizSetKey
	bizSet.WatchFields = []string{common.BKBizSetIDField, common.BKBizSetScopeField}
	if err := newBizSetRelation(context.Background(), bizSet); err != nil {
		blog.Errorf("watch biz set event for biz set relation failed, err: %v", err)
		return err
	}
	blog.Info("watch biz set relation events, watch biz set success")

	// watch biz event
	biz := base
	biz.Key = event.BizKey
	if err := newBizSetRelation(context.Background(), biz); err != nil {
		blog.Errorf("watch biz event for biz set relation failed, err: %v", err)
		return err
	}
	blog.Info("watch biz set relation events, watch biz success")

	return nil
}