code: public CheckUsersSavedTracksRequest.Builder checkUsersSavedTracks(String... ids) {
      return new CheckUsersSavedTracksRequest.Builder(accessToken)
              .setDefaults(httpManager, scheme, host, port)
              .ids(concat(ids, ','));
    }
docs: Check if a track is saved in the users "Your Music" library.
  
  @param ids The tracks IDs to check for in the user's Your Music library. Maximum: 50 IDs.
  @return A builder object that can be used to check if an user has saved a track.