List chunk(List list, int chunkSize) {
  List chunks = [];
  int len = list.length;
  for (var i = 0; i < len; i += chunkSize) {
    int size = i+chunkSize;
    chunks.add(list.sublist(i, size > len ? len : size));
  }
  return chunks;
}

List nums = [1,2,3,4,5];

print(chunk(nums, 2));

// [[1,2], [3,4], [5]]