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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def subscriber_choice_control(self):
 """ It controls subscribers choice and generates error message if there is a non-choice. """

        self.current.task_data['option'] = None
        self.current.task_data['chosen_subscribers'], names = self.return_selected_form_items(
            self.input['form']['SubscriberList'])
        self.current.task_data[
            'msg'] = "You should choose at least one subscriber for migration operation."
        if self.current.task_data['chosen_subscribers']:
            self.current.task_data['option'] = self.input['cmd']
            del self.current.task_data['msg']