let ends_with ~what ?(offset=0) str =
let what_idx = ref ((String.length what) - 1) in
let str_idx = ref ((String.length str) - 1) in
let ok = ref true in
while !ok &&
offset <= !str_idx &&
0 <= !what_idx do
if str.[!str_idx] = what.[!what_idx] then
decr what_idx
else
ok := false;
decr str_idx
done;
if !what_idx = -1 then
true
else
false