Combine15.swift

networkService.request(.login(username: username, password: password))
  .flatMap { token in
      networkService.request(.playlists(token))
  }.flatMap { playlists in
      let playlist = playlists.first
      networkService.request(.songs(for: playlist.id))
  }.sink(receiveCompletion: {  _ in
        UIApplication.shared.isNetworkActivityIndicatorVisible = false
  }, receiveValue: { songs in
        self.configure(with: songs)
  }