isListOfListOfList function
Returns true
if list
elements are all of type List<List>.
Implementation
bool isListOfListOfList(Object? list) {
if (list == null || list is! List) return false;
if (list is List<List<List>>) return true;
if (list.isEmpty) return false;
if (listNotMatchesAll(list, (e) => isListOfList(e))) return false;
return true;
}