*
   * @param sources the sources to concatenate
   * @return a {@code CharSource} containing the concatenated data
   * @since 15.0
   */
  public static CharSource concat(Iterable<? extends CharSource> sources) {
    return new ConcatenatedCharSource(sources);
  }

  /**
   * Concatenates multiple {@link CharSource} instances into a single source. Streams returned from

    assertFalse(CharSource.concat(c1, c2, c3).isEmpty());

    CharSource emptyConcat = CharSource.concat(CharSource.empty(), CharSource.empty());
    assertTrue(emptyConcat.isEmpty());
  }

  public void testConcat_infiniteIterable() throws IOException {
    CharSource source = CharSource.wrap("abcd");
    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

      try (SeekableByteChannel channel = Files.newByteChannel(path, options)) {
        return ByteStreams.toByteArray(Channels.newInputStream(channel), channel.size());
      }
    }

    @Override
    public CharSource asCharSource(Charset charset) {
      if (options.length == 0) {
        // If no OpenOptions were passed, delegate to Files.lines, which could have performance

      try (SeekableByteChannel channel = Files.newByteChannel(path, options)) {
        return ByteStreams.toByteArray(Channels.newInputStream(channel), channel.size());
      }
    }

    @Override
    public CharSource asCharSource(Charset charset) {
      if (options.length == 0) {
        // If no OpenOptions were passed, delegate to Files.lines, which could have performance