function fill(out, start, end) {
  if (end - start > 1) {
    const middle = Math.floor((start + end) / 2);
    fill(out, start, middle);
    fill(out, middle, end);
  } else if (start < end) {
    out[start] = start * 2;
  }
}
export function allocated(size) {
  const out = new Array(size);
  fill(out, 0, size);
  return out;
}