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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def countries(instance):
 """Ensure that the `country` property of `location` objects is a valid ISO 3166-1 ALPHA-2 Code. """

    if (instance['type'] == 'location' and 'country' in instance and not
            instance['country'].upper() in enums.COUNTRY_CODES):

        return JSONError("Location `country` should be a valid ISO 3166-1 "
                         "ALPHA-2 Code.",
                         instance['id'], 'marking-definition-type')