private static void shiftTailLeftOnLevel(int[] indentArray, int upper, int bottom, int level) {
    for (int i = upper; i < bottom; i++) {
      if (indentArray[i] < level) {
        throw new IllegalStateException("Current indentation is less then subtracted level.");
      }
      indentArray[i] -= level;
    }
  }
private static void shiftTailLeftOnLevel(int[] indentArray, int upper, int bottom, int level)