/**
   * Returns a {@code ByteSource} that reads base-encoded bytes from the specified {@code
   * CharSource}.
   */
  @J2ktIncompatible
  @GwtIncompatible // ByteSource,CharSource
  public final ByteSource decodingSource(CharSource encodedSource) {
    checkNotNull(encodedSource);
    return new ByteSource() {
      @Override
      public InputStream openStream() throws IOException {

  }

  /**
   * Returns a new {@link ByteSource} for reading bytes from the given file.
   *
   * @since 14.0
   */
  public static ByteSource asByteSource(File file) {
    return new FileByteSource(file);
  }

  private static final class FileByteSource extends
      ByteSource
  {

    private final File file;

    private FileByteSource(File file) {

    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice
    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();
    Reader reader = concatenated.openStream(); // no need to worry about closing
    for (int i = 0; i < 8; i++) {

  }

  /**
   * Returns a new {@link ByteSource} for reading bytes from the given file.
   *
   * @since 14.0
   */
  public static ByteSource asByteSource(File file) {
    return new FileByteSource(file);
  }

  private static final class FileByteSource extends
      ByteSource
  {

    private final File file;

    private FileByteSource(File file) {

    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice
    // TODO(cgdecker): Add CharSource.slice?
    StringBuilder builder = new StringBuilder();
    Reader reader = concatenated.openStream(); // no need to worry about closing
    for (int i = 0; i < 8; i++) {