関連ワード:  how to check in python    how to check in python if a number is prime    how to check in python if a string is a number    how to check in python if a number is positive or negative    how to check in python if number is even    how to check in python if a variable exists    how to check in python if string is empty    how to check in python if list is empty    how to check in python if a number is even or odd    how to check in python if a string contains a substring