def branches(self, user, repo, branch=None):
        if branch:
            return [self.repo(user, repo).branch(branch)]
        return self.repo(user, repo).iter_branches() or []

    # TODO: Test
Return True if the supplied 'branch' is ok, False if bad, else None.
dataset/ETHPy150Open CenterForOpenScience/osf.io/website/addons/github/api.py/GitHubClient.branches--crossover with--dataset/ETHPy150Open bloomberg/phabricator-tools/py/abd/abdt_branch.py/calc_is_ok