public final void clear() {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the {@code RangeMap} unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")

      fail("Expected UnsupportedOperationException or NullPointerException.");
    } catch (UnsupportedOperationException | NullPointerException e) {
      // Expected.
    }
    assertInvariants(map);

    try {
      entrySet.addAll(singleton((Entry<K, V>) entryToAdd));
      fail("Expected UnsupportedOperationException or NullPointerException.");
    } catch (UnsupportedOperationException | NullPointerException e) {

      fail("Expected UnsupportedOperationException or NullPointerException.");
    } catch (UnsupportedOperationException | NullPointerException e) {
      // Expected.
    }
    assertInvariants(map);

    try {
      entrySet.addAll(singleton((Entry<K, V>) entryToAdd));
      fail("Expected UnsupportedOperationException or NullPointerException.");
    } catch (UnsupportedOperationException | NullPointerException e) {

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final @Nullable Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  /**
   * {@inheritDoc}

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean add(E e) {
    throw new UnsupportedOperationException();
  }

  /**

   * <p>A collection is considered immutable if:
   *
   * <ol>
   *   <li>All its mutation methods result in UnsupportedOperationException, and do not change the
   *       underlying contents.
   *   <li>All methods that return objects that can indirectly mutate the collection throw
   *       UnsupportedOperationException when those mutators are called.
   * </ol>
   *
   * @param collection the presumed-immutable collection

                      }

                      @Override
                      public Iterator<String> iterator() {
                        throw new UnsupportedOperationException();
                      }

                      @Override
                      public boolean removeAll(Collection<?> collection) {
                        throw new UnsupportedOperationException();

    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the multimap unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")

      fail(message);
    } catch (UnsupportedOperationException expected) {
    }
  }

  private void expectReturnsFalseOrThrows(Target target) {
    String message = Platform.format("retainAll(%s) should return false or throw", target);
    try {
      assertFalse(message, collection.retainAll(target.toRetain));
    } catch (UnsupportedOperationException tolerated) {
    }
  }

   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public void addAll(RangeSet<C> other) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the {@code RangeSet} unmodified.
   *
   * @throws UnsupportedOperationException always