* Each tag configuration follows the pattern: tagname[attr=value].classname#id
     *
     * Examples:
     * - "div.content" matches div elements with class "content"
     * - "span#header" matches span elements with ID "header"
     * - "p[data-type=ad]" matches p elements with data-type attribute equal to "ad"
     *
     * @param value the comma-separated string of pruned tag configurations

  public void testSet_replacingNull() {
    E[] elements = createSamplesArray();
    int i = aValidIndex();
    elements[i] = null;
    collection = getSubjectGenerator().create(elements);

    doTestSet(e3());
  }

  private void doTestSet(E newValue) {
    int index = aValidIndex();
    E initialValue = getList().get(index);
    assertEquals(
        "set(i, x) should return the old element at position i.",
        initialValue,

    Iterator<E> iterator = collection.iterator();
    Object element = iterator.next();
    // If it's an Entry, it may become invalid once it's removed from the Map. Copy it.
    if (element instanceof Entry) {
      Entry<?, ?> entry = (Entry<?, ?>) element;
      element = mapEntry(entry.getKey(), entry.getValue());
    }
    assertTrue(collection.contains(element)); // sanity check
    iterator.remove();

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *
   * @throws IllegalArgumentException if the stream consists of two or more elements.
   * @throws NullPointerException if any element in the stream is {@code null}.
   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.

  public static Test suite() {
    return SetTestSuiteBuilder.using(
            new TestStringSetGenerator() {
              @Override
              protected Set<String> create(String[] elements) {
                return MinimalSet.of(elements);
              }
            })
        .named("MinimalSet")
        .withFeatures(
            CollectionFeature.ALLOWS_NULL_VALUES, CollectionFeature.NONE, CollectionSize.ANY)

   * inserted into the multiset must implement the {@code Comparable} interface. Furthermore, all
   * such elements must be <i>mutually comparable</i>: {@code e1.compareTo(e2)} must not throw a
   * {@code ClassCastException} for any elements {@code e1} and {@code e2} in the multiset. If the

import java.util.NoSuchElementException;
import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of the {@code Iterator} interface for sequences
 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * {@snippet :
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {

                new TestStringSetGenerator() {
                  @Override
                  protected Set<String> create(String[] elements) {
                    return new StandardImplForwardingNavigableSet<>(
                        new SafeTreeSet<String>(asList(elements)));
                  }

                  @Override
                  public List<String> order(List<String> insertionOrder) {

 */
@GwtCompatible
public class Joiner {
  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(String separator) {
    return new Joiner(separator);
  }

  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(char separator) {
    return new Joiner(String.valueOf(separator));
  }

    //     ends up at a[d], which in turn ends up at a[2d], and so on until we get back to a[0].
    //     (All indices taken mod n.) If d and n are mutually prime, all elements will have been
    //     moved at that point. Otherwise, we can rotate the cycle a[1], a[1 + d], a[1 + 2d], etc,
    //     then a[2] etc, and so on until we have rotated all elements. There are gcd(d, n) cycles