/**
 * Implementation of {@link ImmutableList} with exactly one element.
 *
 * @author Hayward Chan
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace(), not default serialization
final class SingletonImmutableList<E> extends ImmutableList<E> {

  final transient E element;

  SingletonImmutableList(E element) {
    this.element = checkNotNull(element);
  }

  @Override
  public E get(int index) {

	default:
		return "unknown"
	}
}

// AccElem holds information for calculating an average value
type AccElem struct {
	Total int64
	Size  int64
	N     int64
}

// Add a duration to a single element.
func (a *AccElem) add(dur time.Duration) {
	if dur < 0 {
		dur = 0
	}
	a.Total += int64(dur)
	a.N++
}

// Merge b into a.
func (a *AccElem) merge(b AccElem) {
	a.N += b.N
	a.Total += b.Total

     *
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        StringBuilder ret = new StringBuilder();
        for (final byte element : this.b) {
            final int n = element & 0xff;
            if (n <= 0x0f) {
                ret.append("0");
            }
            ret.append(Integer.toHexString(n));
        }
        return ret.toString();
    }

 */
final class SingletonImmutableList<E> extends ForwardingImmutableList<E> {
  private final transient List<E> delegate;
  private final E element;

  SingletonImmutableList(E element) {
    this.delegate = singletonList(checkNotNull(element));
    this.element = element;
  }

  @Override
  List<E> delegateList() {
    return delegate;
  }

import java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/**
 * Base class for collection testers.
 *
 * @param <E> the element type of the collection to be tested.
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import java.util.Collection;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;
import org.junit.Ignore;

/**
 * Base class for collection testers.
 *
 * @param <E> the element type of the collection to be tested.
 * @author Kevin Bourrillion
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

        return@binarySearch target.compareTo(b0b1)
      }

    return when {
      offset >= 0 -> offset * 4 // This section was found by binary search.
      else -> (-offset - 2) * 4 // Not found? Use the preceding element.
    }
  }

  /**
   * Binary search [ranges] for [codePoint], looking at its bottom 7 bits.
   *
   * This binary searches over 4-byte entries, and so it needs to adjust binary search indices

  @Override
  void setCountCheckReturnValue(E element, int count) {
    assertTrue(
        "setCount() with the correct expected present count should return true",
        setCount(element, count));
  }

  @Override
  void setCountNoCheckReturnValue(E element, int count) {
    setCount(element, count);
  }

  @CanIgnoreReturnValue
  private boolean setCount(E element, int count) {

    final int hash;

    Element(int hash) {
      this.hash = hash;
    }

    @Override
    public boolean equals(@Nullable Object obj) {
      return this == obj || (obj instanceof Element && ((Element) obj).hash == hash);
    }

    @Override
    public int hashCode() {
      return hash;
    }

    @Override
    public int compareTo(Element that) {

    List<Object> list = new ArrayList<>(equalityGroup.length);
    for (int i = 0; i < equalityGroup.length; i++) {
      Object element = equalityGroup[i];
      if (element == null) {
        throw new NullPointerException("at index " + i);
      }
      list.add(element);
    }
    equalityGroups.add(list);
    return this;
  }

  /** Run tests on equals method, throwing a failure on an invalid test */