関連ワード:  how to check list is null in python    how to check list is empty in python    how to find list is empty in python    how to check list is not empty in python    how to check whether list is empty in python    how to check if list is none in python    how to check if list is not null in python    how to check if a list value is null in python    how to find if list is empty in python    how to check if a linked list is empty in python