* whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * <pre>{@code
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {
 *         return (previous == 1 << 30) ? null : previous * 2;
 *       }
 *     };
 * }</pre>
 *

 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * <pre>{@code
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {
 *         return (previous == 1 << 30) ? null : previous * 2;
 *       }
 *     };
 * }</pre>
 *