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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 add_content_ratings(self, app_id, submission_id, security_code):
 """Add content ratings to the web app identified by by ``app_id``, using the specified submission id and security code. :returns: HttpResponse: * status_code (int) 201 is successful """

        url = self.url('content_ratings') % app_id
        return self.conn.fetch('POST', url,
                               {'submission_id': '%s' % submission_id,
                                'security_code': '%s' % security_code
                                })