monitor.enter();
      try {
        int i = lastRet;
        if (i == -1) throw new IllegalStateException();
        lastRet = -1;

        int ti = takeIndex;
        removeAt(i);
        // back up cursor (reset to front if was first element)
        nextIndex = (i == ti) ? takeIndex : i;
        checkNext();
      } finally {
        monitor.leave();
      }
    }
  }

      monitor.enter();
      try {
        int i = lastRet;
        if (i == -1) throw new IllegalStateException();
        lastRet = -1;

        int ti = takeIndex;
        removeAt(i);
        // back up cursor (reset to front if was first element)
        nextIndex = (i == ti) ? takeIndex : i;
        checkNext();
      } finally {
        monitor.leave();
      }
    }
  }