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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 ids(self):
 """ Returns set with all todo IDs. """

        if config().identifiers() == 'text':
            ids = self._id_todo_map.keys()
        else:
            ids = [str(i + 1) for i in range(self.count())]
        return set(ids)