class PersistenceOperations {

  @Nonnull
  public Single<Boolean> fileContainsShare(@Nonnull final File file) {
    checkNotNull(file, "\'file\' cannot be null.");
    
    return rxFiles
        .readStringFromFile(file, CharsetConstants.SHARE_FILE_CHARSET)
        .flatMap(shareSerialiser::isValidSerialisation);
  }

  public  PersistenceOperations(
      @Nonnull final ShareSerialiser shareSerialiser,
      @Nonnull final RecoverySchemeSerialiser recoverySchemeSerialiser,
      @Nonnull final RxFiles rxFiles);

}