* contained in this set. This is equivalent to {@code range(CLOSED, CLOSED)}.
   *
   * @throws NoSuchElementException if this set is empty
   */
  public abstract Range<C> range();

  /**
   * Returns the minimal range with the given boundary types for which all values in this set are
   * {@linkplain Range#contains(Comparable) contained} within the range.
   *

   * contained in this set. This is equivalent to {@code range(CLOSED, CLOSED)}.
   *
   * @throws NoSuchElementException if this set is empty
   */
  public abstract Range<C> range();

  /**
   * Returns the minimal range with the given boundary types for which all values in this set are
   * {@linkplain Range#contains(Comparable) contained} within the range.
   *

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

/**
 * An immutable object that may contain a non-null reference to another object. Each instance of
 * this type either contains a non-null reference, or contains nothing (in which case we say that
 * the reference is "absent"); it is never said to "contain {@code null}".
 *
 * <p>A non-null {@code Optional<T>} reference can be used as a replacement for a nullable {@code T}

   * </ol>
   *
   * @param multimap the presumed-immutable multimap
   * @param sampleKey a key of the same type as that contained by {@code multimap}. {@code multimap}
   *     may or may not have {@code sampleKey} as a key.
   * @param sampleValue a key of the same type as that contained by {@code multimap}. {@code
   *     multimap} may or may not have {@code sampleValue} as a key.
   */

 *   <li>Instances of this type are obtained using the static factory methods in this class.
 *   <li>Ranges are <i>convex</i>: whenever two values are contained, all values in between them
 *       must also be contained. More formally, for any {@code c1 <= c2 <= c3} of type {@code C},
 *       {@code r.contains(c1) && r.contains(c3)} implies {@code r.contains(c2)}). This means that a

    boolean contained = false;
    if (actual instanceof Collection) {
      contained = ((Collection<?>) actual).contains(expected);
    } else {
      for (Object o : actual) {
        if (equal(o, expected)) {
          contained = true;
          break;
        }
      }
    }

    if (!contained) {
      fail("Not true that " + actual + " contains " + expected);

   * </ol>
   *
   * @param multimap the presumed-immutable multimap
   * @param sampleKey a key of the same type as that contained by {@code multimap}. {@code multimap}
   *     may or may not have {@code sampleKey} as a key.
   * @param sampleValue a key of the same type as that contained by {@code multimap}. {@code
   *     multimap} may or may not have {@code sampleValue} as a key.
   */

  /**
   * Determines whether this multiset contains the specified element.
   *
   * <p>This method refines {@link Collection#contains} to further specify that it <b>may not</b>
   * throw an exception in response to {@code element} being null or of the wrong type.
   *
   * @param element the element to check for
   * @return {@code true} if this multiset contains at least one occurrence of the element
   */
  @Override

    boolean contained = false;
    if (actual instanceof Collection) {
      contained = ((Collection<?>) actual).contains(expected);
    } else {
      for (Object o : actual) {
        if (equal(o, expected)) {
          contained = true;
          break;
        }
      }
    }

    if (!contained) {
      fail("Not true that " + actual + " contains " + expected);

  }

  /**
   * Returns {@code true} if the collection {@code self} contains all of the elements in the
   * collection {@code c}.
   *
   * <p>This method iterates over the specified collection {@code c}, checking each element returned
   * by the iterator in turn to see if it is contained in the specified collection {@code self}. If
   * all elements are so contained, {@code true} is returned, otherwise {@code false}.
   *