code: public void sleep(String sleepMillis) throws NumberFormatException {
  
          try {
              Thread.sleep(Long.parseLong(sleepMillis));
          } catch (InterruptedException e) {
              // ignore
          }
      }
docs: Sleeps for a duration given in milliseconds.<p>
  
  @param sleepMillis a string containing the number of milliseconds to wait
  
  @throws NumberFormatException if the sleepMillis parameter is not a valid number