let int32 = new Int32Array(2 ** 20)
let int16 = new Int16Array(int32.buffer)
let int8 = new Int8Array(int32.buffer)
function fill(arr, value) {
  arr[0] = value
  let l = arr.length
  let i = 1
  for (; i < l; i *= 2) {
    arr.copyWithin(i, 0, i)
  }
  i /= 2
  return arr
}