Is it possible to import a flutter package inside the custom function not custom action

Possible to add flutter packages in custom function.
Example:
I want to import this package below package inside custom function

import 'package:cron/cron.dart';
int postCurrentLocationUsingAPI(double? amount) {
var cron = new Cron();
cron.schedule(new Schedule.parse('*/3 '), () async {
print('every three minutes');
});