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Solve the following problem using Python, implementing the functions described below, one line at a time
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<USER_TASK:>
Description:
 def task_add_user(self, *args, **kwargs):
 """Add users to the current task :returns: None :rtype: None :raises: None """

        if not self.cur_task:
            return

        dialog = UserAdderDialog(task=self.cur_task)
        dialog.exec_()
        users = dialog.users
        for user in users:
            userdata = djitemdata.UserItemData(user)
            treemodel.TreeItem(userdata, self.task_user_model.root)