throw ERT.badarg(bin, idx);
}
long split = i.value*8;
return new ETuple2(b.substring(0, split),
b.substring(split));
/* more efficient, but works only for EBinary */
// return new ETuple2(b.sub_binary(0, i.value),
// b.sub_binary(i.value, b.byteSize()-i.value));