private static final String LOWER = "abcdefghijklmnopqrstuvwxyz";
  private static final String UPPER = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

  public void testToLowerCase() {
    assertEquals(LOWER, Ascii.toLowerCase(UPPER));
    assertSame(LOWER, Ascii.toLowerCase(LOWER));
    assertEquals(IGNORED, Ascii.toLowerCase(IGNORED));

    int lower = 0;
    int upper = list.size() - 1;

    while (lower <= upper) {
      int middle = (lower + upper) >>> 1;
      int c = comparator.compare(key, list.get(middle));
      if (c < 0) {
        upper = middle - 1;
      } else if (c > 0) {
        lower = middle + 1;
      } else {
        return lower
            + presentBehavior.resultIndex(

   * (inclusive) to {@code upper} (inclusive). (These are the same values contained in {@code
   * Range.closed(lower, upper)}.)
   *
   * @throws IllegalArgumentException if {@code lower} is greater than {@code upper}
   * @since 23.0
   */
  public static ContiguousSet<Integer> closed(int lower, int upper) {
    return create(Range.closed(lower, upper), DiscreteDomain.integers());
  }

  }

  @CollectionSize.Require(SEVERAL)
  public void testLowerHole() {
    resetWithHole();
    assertEquals(null, navigableSet.lower(a));
    assertEquals(a, navigableSet.lower(b));
    assertEquals(a, navigableSet.lower(c));
  }

  @CollectionSize.Require(SEVERAL)
  public void testFloorHole() {
    resetWithHole();
    assertEquals(a, navigableSet.floor(a));

  public Iterator<E> iterator() {
    return delegate.iterator();
  }

  @Override
  public E last() {
    return delegate.last();
  }

  @Override
  public @Nullable E lower(E e) {
    return delegate.lower(checkValid(e));
  }

  @Override
  public @Nullable E pollFirst() {
    return delegate.pollFirst();
  }

  @Override
  public @Nullable E pollLast() {

  }

  @Override
  @GwtIncompatible("NavigableSet")
  ImmutableSortedSet<E> createDescendingSet() {
    throw new AssertionError("should never be called");
  }

  @Override
  @CheckForNull
  public E lower(E element) {
    return forward.higher(element);
  }

  @Override
  @CheckForNull
  public E floor(E element) {
    return forward.ceiling(element);
  }

  @Override
  @CheckForNull

    }

    @Override
    public BaseEncoding lowerCase() {
      BaseEncoding result = lowerCase;
      if (result == null) {
        Alphabet lower = alphabet.lowerCase();
        result = lowerCase = (lower == alphabet) ? this : newInstance(lower, paddingChar);
      }
      return result;
    }

    @Override
    public BaseEncoding ignoreCase() {
      BaseEncoding result = ignoreCase;

    int index =
        SortedLists.binarySearch(
            ranges,
            Range::lowerBound,
            Cut.belowValue(key),
            KeyPresentBehavior.ANY_PRESENT,
            KeyAbsentBehavior.NEXT_LOWER);
    if (index == -1) {
      return null;
    } else {
      Range<K> range = ranges.get(index);
      return range.contains(key) ? values.get(index) : null;
    }
  }

  @Override

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.GwtIncompatible;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;
import static java.util.Objects.requireNonNull;

import com.google.common.annotations.Beta;