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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 list_deploy_keys(self, auth, username, repo_name):
 """ List deploy keys for the specified repo. :param auth.Authentication auth: authentication object :param str username: username of owner of repository :param str repo_name: the name of the repo :return: a list of deploy keys for the repo :rtype: List[GogsRepo.DeployKey] :raises NetworkFailure: if there is an error communicating with the server :raises ApiFailure: if the request cannot be serviced """

        response = self.get("/repos/{u}/{r}/keys".format(u=username, r=repo_name), auth=auth)
        return [GogsRepo.DeployKey.from_json(key_json) for key_json in response.json()]