*     helpful predefined constants
   * @return the buffered reader
   */
  public static BufferedReader newReader(File file, Charset charset) throws FileNotFoundException {
    checkNotNull(file);
    checkNotNull(charset);
    return new BufferedReader(new InputStreamReader(new FileInputStream(file), charset));
  }

  /**
   * Returns a buffered writer that writes to a file using the given character set.
   *

      Comparator<? super E> comparator, E... elements) {
    checkNotNull(elements);
    switch (elements.length) {
      case 0:
        return emptySet(comparator);
      default:
        SortedSet<E> delegate = new TreeSet<E>(comparator);
        for (E element : elements) {
          checkNotNull(element);
          delegate.add(element);
        }

      @ParametricNullness E key,
      Comparator<? super E> comparator,
      KeyPresentBehavior presentBehavior,
      KeyAbsentBehavior absentBehavior) {
    checkNotNull(comparator);
    checkNotNull(list);
    checkNotNull(presentBehavior);
    checkNotNull(absentBehavior);
    if (!(list instanceof RandomAccess)) {
      list = new ArrayList<>(list);
    }

        return new String(factoryExpectedForNothing, UTF_8) + checkNotNull(data);
      }

      @Override
      public void tearDown() throws IOException {
        factory.tearDown();
      }
    };
  }

  public static ByteSourceFactory asSlicedByteSourceFactory(
      ByteSourceFactory factory, long off, long len) {
    checkNotNull(factory);
    return new ByteSourceFactory() {
      @Override

   */
  public static <T extends @Nullable Object> Predicate<T> and(
      Predicate<? super T> first, Predicate<? super T> second) {
    return new AndPredicate<>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
  }

  /**
   * Returns a predicate that evaluates to {@code true} if any one of its components evaluates to

   */
  public void callAndAssertThrows(
      Class<? extends Throwable> expected, String methodName, Object... arguments)
      throws Exception {
    checkNotNull(expected);
    checkNotNull(methodName);
    checkNotNull(arguments);
    sendRequest(methodName, arguments);
    assertThat(getResponse(methodName).getThrowable()).isInstanceOf(expected);
  }

  /**

    checkNotNull(fromElement);
    checkNotNull(toElement);
    checkArgument(comparator().compare(fromElement, toElement) <= 0);
    return subSetImpl(fromElement, true, toElement, false);
  }

  /**
   * @since 12.0
   */
  @GwtIncompatible // NavigableSet
  @Override
  public ContiguousSet<C> subSet(
      C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
    checkNotNull(fromElement);

  }

  @Override
  public boolean hasEdgeConnecting(N nodeU, N nodeV) {
    checkNotNull(nodeU);
    checkNotNull(nodeV);
    return nodes().contains(nodeU) && successors(nodeU).contains(nodeV);
  }

  @Override
  public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
    checkNotNull(endpoints);
    if (!isOrderingCompatible(endpoints)) {
      return false;
    }

        return join(parts.iterator());
      }

      @Override
      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
        checkNotNull(appendable, "appendable");
        checkNotNull(parts, "parts");
        while (parts.hasNext()) {
          Object part = parts.next();
          if (part != null) {
            appendable.append(Joiner.this.toString(part));

@NullUnmarked
class RandomAmountInputStream extends FilterInputStream {
  private final Random random;

  public RandomAmountInputStream(InputStream in, Random random) {
    super(checkNotNull(in));
    this.random = checkNotNull(random);
  }

  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    return super.read(b, off, random.nextInt(len) + 1);
  }