save method Null safety
save the list
Implementation
static void save({
required String name,
required String subject,
}) async {
final pref = await SharedPreferences.getInstance();
/// get already stored list of papers for the subject
final myPapers = pref.getStringList(subject);
final List<String> myList = myPapers ?? [];
myList.add(name);
///save the list of papers
pref.setStringList(subject, myList);
}