関連ワード:  how to define null variable in python    how to define empty variable in python    how to define null value in python    how to define undefined variable in python    how to assign null value in python    how to set null value in python    how to assign null value in python pandas    how to assign empty variable in python    how to define empty int variable in python    how to assign null to variable in python  
結果 : how to define null variable in python