void removeAt(int i) {
    E[] items = this.items;
    // if removing front item, just advance
    if (i == takeIndex) {
      items[takeIndex] = null;
      takeIndex = inc(takeIndex);
    } else {
      // slide over all others up through putIndex.
      for (; ; ) {
        int nexti = inc(i);
        if (nexti != putIndex) {
          items[i] = items[nexti];
          i = nexti;
        } else {