[Question] Use `sjson.Delete` in a way to delete not present fields

[manuelarte]

Hi,

So Imagine I have the following JSON:

{
 "id": 1,
 "name": "John",
 "surname": "Doe",
 "age": 18,
 "address": {
   "street": "mystreet",
   "city": "mycity",
   "country": "mycountry",
   "zipcode": "1111"
 }
}

With your (amazing) library, it's possible to do, sjson.Delete(json, "name"), but do you know any way to do the "opposite", to let's say delete every field but some of them, something like:

sjson.Keep(json, "name,surname"), resulting in:

{
 "name": "John",
 "surname": "Doe"
}

Thanks