}

  /**
   * @since 12.0
   */
  @Override
  public @Nullable E ceiling(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, true), null);
  }

  /**
   * @since 12.0
   */
  @GwtIncompatible // NavigableSet
  @Override
  public @Nullable E higher(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, false), null);
  }

  @Override
  public E first() {

   * NavigableSets inherit the tests for filtered Iterables, Collections, Sets, and SortedSets. The
   * actual implementation tests are further down.
   */

  public abstract static class AbstractFilteredIterableTest<C extends Iterable<Integer>>
      extends TestCase {
    abstract C createUnfiltered(Iterable<Integer> contents);

    abstract C filter(C elements, Predicate<? super Integer> predicate);

import com.google.common.collect.ImmutableSortedMultiset;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.Iterables;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.LinkedHashMultiset;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;

import static java.util.concurrent.TimeUnit.SECONDS;
import static org.junit.Assert.assertThrows;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import com.google.common.testing.NullPointerTester;
import com.google.common.testing.TestLogHandler;
import com.google.common.util.concurrent.Service.State;

 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.Iterables.transform;
import static com.google.common.collect.Iterators.mergeSorted;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtCompatible;

import com.google.common.collect.ImmutableSortedMultiset;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.Iterables;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.LinkedHashMultiset;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Lists;

  private static final Iterable<Integer> SOME_ITERABLE = new SomeIterable();

  private static final class RemoveFirstFunction implements Function<String, String>, Serializable {
    @Override
    public String apply(String from) {
      return (from.length() == 0) ? from : from.substring(1);
    }
  }

  private static class SomeIterable implements Iterable<Integer>, Serializable {
    @Override

    }

    @Override
    public Optional<Long> sizeIfKnown() {
      if (!(sources instanceof Collection)) {
        // Infinite Iterables can cause problems here. Of course, it's true that most of the other
        // methods on this class also have potential problems with infinite  Iterables. But unlike
        // those, this method can cause issues even if the user is dealing with a (finite) slice()

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
import static com.google.common.collect.Iterables.getOnlyElement;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;

  }

  private final class AsMapOfRanges extends IteratorBasedAbstractMap<Range<K>, V> {

    final Iterable<Entry<Range<K>, V>> entryIterable;

    @SuppressWarnings("unchecked") // it's safe to upcast iterables
    AsMapOfRanges(Iterable<RangeMapEntry<K, V>> entryIterable) {
      this.entryIterable = (Iterable) entryIterable;
    }

    @Override
    public boolean containsKey(@Nullable Object key) {