* } finally {
 *   monitor.leave();
 * }
 * }</pre>
 *
 * <p>A call to any of the <i>enter</i> methods with <b>boolean</b> return type should always appear
 * as the condition of an <i>if</i> statement containing a <i>try/finally</i> block to ensure that
 * the current thread leaves the monitor cleanly:
 *
 * <pre>{@code
 * if (monitor.tryEnter()) {
 *   try {
 *     // do things while occupying the monitor