selectAll method
Implementation
void selectAll(List<int> indexes) {
var set = _selectIndexes.value;
var data = indexes
.map((index) => _IndexedData(index, _dataSubject.value.list[index]))
.map(set.add)
.reduce((value, element) => value || element);
if (data) {
_selectIndexes.add(set);
}
}