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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 _process_mark_toggle(self, p_todo_id, p_force=None):
 """ Adds p_todo_id to marked_todos attribute and returns True if p_todo_id is not already marked. Removes p_todo_id from marked_todos and returns False otherwise. p_force parameter accepting 'mark' or 'unmark' values, if set, can force desired action without checking p_todo_id presence in marked_todos. """

        if p_force in ['mark', 'unmark']:
            action = p_force
        else:
            action = 'mark' if p_todo_id not in self.marked_todos else 'unmark'

        if action == 'mark':
            self.marked_todos.add(p_todo_id)
            return True
        else:
            self.marked_todos.remove(p_todo_id)
            return False