TweetRepositoryImpl returns an Observable of Tweets by a flow builder emitting from DB and DB fresh from network

TweetRepositoryImpl.kt

fun getSearchTweets(query: String)
: Observable<List<Tweet>> =
flow<List<Tweet>> {
      val accessToken = tokenDBDataSource.getAccessToken()?: throw BadTokenException("No token was found")
      val token = accessToken.token
      // retrieve old values from DB
      emit(tweetsDBDataSource.retrieveAllTweetsForTweetsIds(tweetIds))
      // get fresh values from network & saved them into DB
      val eitherResult = networkDataSource.search(token, query)
      val tweets = mapperTweets.map(eitherResult)
      tweetQueryJoinDBDataSource.deleteTweets(query)
      tweetDBDataSource.insertTweets(tweets)
      insertQuery(query)
      tweetQueryJoinDBDataSource.insertQueryAndTweetsId(tweetQueryJoinDBDataSource.convert(tweets, query))
      // saved network into DB & emit fresh values from DB
      val tweetIds = tweetQueryJoinDBDataSource.retrieveAllTweetsIdAQuery(query)
      emit(tweetsDataSource.retrieveAllTweetsForTweetsIds(tweetIds))
}.flowOn(taskThreading.ioDispatcher())
    .asObservable()