* keys and values are the result of applying the provided mapping functions to the input
   * elements.
   *
   * <p>If the mapped keys contain duplicates (according to the comparator), the values are merged
   * using the specified merging function. Entries will appear in the encounter order of the first
   * occurrence of the key.
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */

   * keys and values are the result of applying the provided mapping functions to the input
   * elements.
   *
   * <p>If the mapped keys contain duplicates (according to the comparator), the values are merged
   * using the specified merging function. Entries will appear in the encounter order of the first
   * occurrence of the key.
   *
   * @since 21.0
   */
  public static <T extends @Nullable Object, K, V>

  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
      PeekingIterator<T> iterator) {
    return checkNotNull(iterator);
  }

  /**
   * Returns an iterator over the merged contents of all given {@code iterators}, traversing every
   * element of the input iterators. Equivalent entries will not be de-duplicated.
   *

    }
    try {
      unmod.compute(4, (k, v) -> v);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.merge(4, "four", (k, v) -> v);
      fail("UnsupportedOperationException expected");
    } catch (UnsupportedOperationException expected) {
    }
    try {
      unmod.clear();

   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.
   *
   * TODO(cpovirk): Elaborate on this / merge with other comment?
   */
  public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typeArg) {
    TypeResolver resolver =
        new TypeResolver()
            .where(

  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
      PeekingIterator<T> iterator) {
    return checkNotNull(iterator);
  }

  /**
   * Returns an iterator over the merged contents of all given {@code iterators}, traversing every
   * element of the input iterators. Equivalent entries will not be de-duplicated.
   *