* by delaying the per-stack-frame work until each element is accessed. Roughly speaking:
   *
   * <ul>
   *   <li>{@code getStackTrace} takes {@code stackSize} time to return but then negligible time to
   *       retrieve each element of the returned list.
   *   <li>{@code lazyStackTrace} takes negligible time to return but then {@code 1/stackSize} time

    return new IteratorOperation() {
      @Override
      public @Nullable Object execute(Iterator<?> iterator) {
        @SuppressWarnings("unchecked")
        ListIterator<E> li = (ListIterator<E>) iterator;
        li.set(toInsert);
        return null;
      }
    };
  }

  abstract static class Stimulus<E extends @Nullable Object, T extends Iterator<E>> {
    private final String toString;

   * by delaying the per-stack-frame work until each element is accessed. Roughly speaking:
   *
   * <ul>
   *   <li>{@code getStackTrace} takes {@code stackSize} time to return but then negligible time to
   *       retrieve each element of the returned list.
   *   <li>{@code lazyStackTrace} takes negligible time to return but then {@code 1/stackSize} time

   * IllegalStateException} if it is accessed in any way, with the following exceptions:
   *
   * <ul>
   *   <li>{@code view.equals(view)} evaluates to {@code true} (but any other `equals()` expression
   *       involving {@code view} will throw)
   *   <li>{@code hashCode()} does not throw
   *   <li>if {@code node} is re-added to the graph after having been removed, {@code view}'s
   *       behavior is undefined
   * </ul>
   *

 * and a primitive type and its corresponding wrapper type may map to different values.
 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableClassToInstanceMap}
 *   <li>{@link MutableClassToInstanceMap}
 * </ul>
 *
 * <p>To map a generic type to an instance of that type, use {@link
 * com.google.common.reflect.TypeToInstanceMap} instead.
 *

   *
   * <ul>
   *   <li>If {@code T} is a {@code Class} itself, {@code T} itself is returned.
   *   <li>If {@code T} is a {@link ParameterizedType}, the raw type of the parameterized type is
   *       returned.
   *   <li>If {@code T} is a {@link GenericArrayType}, the returned type is the corresponding array
   *       class. For example: {@code List<Integer>[] => List[]}.

 * and a primitive type and its corresponding wrapper type may map to different values.
 *
 * <h3>Implementations</h3>
 *
 * <ul>
 *   <li>{@link ImmutableClassToInstanceMap}
 *   <li>{@link MutableClassToInstanceMap}
 * </ul>
 *
 * <p>To map a generic type to an instance of that type, use {@link
 * com.google.common.reflect.TypeToInstanceMap} instead.
 *

 *
 * <p>{@code CharSource} provides two kinds of methods:
 *
 * <ul>
 *   <li><b>Methods that return a reader:</b> These methods should return a <i>new</i>, independent
 *       instance each time they are called. The caller is responsible for ensuring that the
 *       returned reader is closed.
 *   <li><b>Convenience methods:</b> These are implementations of common operations that are

 *
 * <ul>
 *   <li><b>Shallow immutability.</b> Elements can never be added, removed or replaced in this
 *       collection. This is a stronger guarantee than that of {@link
 *       Collections#unmodifiableCollection}, whose contents change whenever the wrapped collection
 *       is modified.
 *   <li><b>Null-hostility.</b> This collection will never contain a null element.

      this.size = calculateSize(inputList, comparator);
    }

    /**
     * The number of permutations with repeated elements is calculated as follows:
     *
     * <ul>
     *   <li>For an empty list, it is 1 (base case).
     *   <li>When r numbers are added to a list of n-r elements, the number of permutations is
     *       increased by a factor of (n choose r).
     * </ul>
     */
    private static <E> int calculateSize(