safePickInto = (dst, src, keys) => {
  setPrototypeOf(dst, null);
  if (src) {
    keys::forEach(key => {
      if (hasOwnProperty(src, key)) {
        dst[key] = src[key];
      }
    });
  }
  return dst;
}
If `dst` has a proto, it'll be copied into a new proto:null object