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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 parse_authn_request(self, enc_request, binding=BINDING_HTTP_REDIRECT):
 """Parse a Authentication Request :param enc_request: The request in its transport format :param binding: Which binding that was used to transport the message to this entity. :return: A request instance """


        return self._parse_request(enc_request, AuthnRequest,
                                   "single_sign_on_service", binding)