Array method
Writes each string in array into keyed sub-slots and returns a tracked
PP of length array.length.
Sub-slot keys follow the pattern '<key>_<i>'. key defaults to
'struct'.
Implementation
PP Array(List<String> array, {String? key}) {
final arrayKey = slotKey(key);
final pp = AtPtr(arrayKey, array.length);
for (int i = 0; i < array.length; i++) indexSetterFunc(pp, i, ValueAt('${arrayKey}_$i', array[i]));
return pp;
}