関連ワード:  how to make an empty set in python    how to initialize an empty set in python    how to make a blank set in python    how to do empty set in python    how to create null set in python    how do you create an empty set in python    how to create a new empty set in python    how to create empty set and dictionary in python    how do you define an empty set in python    how do you declare an empty set in python