expected = '1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,';
function slice(a, b) {
return expected;
}
function f() {
var length = 4;
var index = 0;
function get3() {
if (length - index < 3)
return null;
return slice(index, ++index);
}
var bytes = null;
while (bytes = get3()) { }
}
f();