関連ワード:  how to check empty or null in python    how to check string is empty or null in python    how to check list empty or not in python    how to check empty variable in python    how to check string is empty or not in python    how to check file is empty or not in python    how to check dataframe is empty or not in python    how to check queue is empty or not in python    how to check stack is empty or not in python    how to check array is empty or not in python