:sig
struct StringList — ordered list of String values

:params
return value : use methods such as `filter()`, `map()`, `keys()`, `each()`, `unique()`, `sort()`, `some()`, `every()`, and `find()` to derive or inspect lists

:content
`StringList` is an ordered container of `String` values. It inherits normal `std::vector<String>` behavior and adds list helpers for filtering, mapping, indexes, iteration, deduplication, sorting, and predicate checks.

:example
StringList labels = split("a,b,a", ",").unique().map([](String item) { return(to_upper(item)); });
print(join(labels, ","), "\n");

:see
>types
0_String
split
join
2_StringList_filter
2_StringList_map
2_StringList_keys
2_StringList_each
2_StringList_unique
2_StringList_sort
2_StringList_some
2_StringList_every
2_StringList_find