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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 fetch_by_code(self, code):
 """ Returns an AuthorizationCode. :param code: The authorization code. :return: An instance of :class:`oauth2.datatype.AuthorizationCode`. :raises: :class:`AuthCodeNotFound` if no data could be retrieved for given code. """

        if code not in self.auth_codes:
            raise AuthCodeNotFound

        return self.auth_codes[code]