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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 modified_created(instance):
 """`modified` property must be later or equal to `created` property """

    if 'modified' in instance and 'created' in instance and \
            instance['modified'] < instance['created']:
        msg = "'modified' (%s) must be later or equal to 'created' (%s)"
        return JSONError(msg % (instance['modified'], instance['created']),
                         instance['id'])