@Override
  public @Nullable Entry<E> pollFirstEntry() {
    Iterator<Entry<E>> entryIterator = entryIterator();
    if (entryIterator.hasNext()) {
      Entry<E> result = entryIterator.next();
      result = Multisets.immutableEntry(result.getElement(), result.getCount());
      entryIterator.remove();
      return result;
    }
    return null;
  }

  @Override
  public @Nullable Entry<E> pollLastEntry() {

        .containsExactly(immutableEntry("foo", 1), immutableEntry("quux", 3))
        .inOrder();
  }

  public void testInsertionOrderAfterRemoveLast() {
    BiMap<String, Integer> map = HashBiMap.create();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("quux", 3);

    map.remove("quux");
    assertThat(map.entrySet())
        .containsExactly(immutableEntry("foo", 1), immutableEntry("bar", 2))

        .containsExactly(immutableEntry("foo", 1), immutableEntry("quux", 3))
        .inOrder();
  }

  public void testInsertionOrderAfterRemoveLast() {
    BiMap<String, Integer> map = HashBiMap.create();
    map.put("foo", 1);
    map.put("bar", 2);
    map.put("quux", 3);

    map.remove("quux");
    assertThat(map.entrySet())
        .containsExactly(immutableEntry("foo", 1), immutableEntry("bar", 2))

        new Builder<String, Integer>().put(immutableEntry("one", 1)).build();
    assertEquals(asList(1), multimap.get("one"));
  }

  public void testBuilder_withImmutableEntryAndNullContents() {
    Builder<String, Integer> builder = new Builder<>();
    assertThrows(
        NullPointerException.class, () -> builder.put(immutableEntry("one", (Integer) null)));

    @Override
    public SampleElements<Entry<Country, String>> samples() {
      return new SampleElements<>(
          immutableEntry(Country.CANADA, "DOLLAR"),
          immutableEntry(Country.CHILE, "PESO"),
          immutableEntry(Country.UK, "POUND"),
          immutableEntry(Country.JAPAN, "YEN"),
          immutableEntry(Country.SWITZERLAND, "FRANC"));
    }

    @SuppressWarnings("unchecked")
    @Override

    assertTrue(entrySet.contains(immutableEntry(10, 'X')));
    assertTrue(entrySet.contains(immutableEntry(20, 'X')));
    assertFalse(entrySet.contains(immutableEntry(15, 'X')));
    entrySet = row.tailMap(15).entrySet();
    assertFalse(entrySet.contains(immutableEntry(10, 'X')));
    assertTrue(entrySet.contains(immutableEntry(20, 'X')));
    assertFalse(entrySet.contains(immutableEntry(15, 'X')));
  }

            Maps.<@Nullable String, Integer>immutableEntry(null, 7),
            Maps.<@Nullable String, Integer>immutableEntry(null, 3),
            Maps.<@Nullable String, Integer>immutableEntry(null, 1),
            Maps.<String, @Nullable Integer>immutableEntry("tree", null),
            immutableEntry("tree", 0),
            immutableEntry("google", 6),
            immutableEntry("google", 2))
        .inOrder();
  }

        ImmutableList.of(
            immutableEntry("foo", 99), immutableEntry("foo", 88), immutableEntry("bar", 77));

    for (int startIndex : new int[] {0, 3, 5}) {
      List<Entry<String, Integer>> list =
          Lists.newArrayList(
              immutableEntry("foo", 2),
              immutableEntry("foo", 3),
              immutableEntry("bar", 4),
              immutableEntry("bar", 5),

    assertThat(map.entrySet())
        .containsExactly(immutableEntry("one", 1), immutableEntry("three", 3))
        .inOrder();
  }

  public void testHeadMapExclusive() {
    Map<String, Integer> map =
        ImmutableSortedMap.of("one", 1, "two", 2, "three", 3).headMap("three", false);
    assertThat(map.entrySet()).containsExactly(immutableEntry("one", 1));
  }

  public void testTailMapInclusive() {

    assertThat(builder.build().entries()).containsExactly(Maps.immutableEntry("key", "value"));
  }

  public void testBuilderWithExpectedKeysPositive() {
    ImmutableSetMultimap.Builder<String, String> builder =
        ImmutableSetMultimap.builderWithExpectedKeys(1);
    builder.put("key", "value");
    assertThat(builder.build().entries()).containsExactly(Maps.immutableEntry("key", "value"));
  }