static boolean isInstance(Conf curr, Conf prev) {
    if (curr.insnIndex != prev.insnIndex) {
      return false;
    }
    Frame<BasicValue> currFr = curr.frame;
    Frame<BasicValue> prevFr = prev.frame;
    for (int i = 0; i < currFr.getLocals(); i++) {
      if (!isInstance(currFr.getLocal(i), prevFr.getLocal(i))) {
        return false;
      }
    }
    for (int i = 0; i < currFr.getStackSize(); i++) {
      if (!isInstance(currFr.getStack(i), prevFr.getStack(i))) {
        return false;
      }
    }
    return true;
  }
static boolean isInstance(Conf curr, Conf prev)