def protect(repo, branch_name='master'):
    """Protect the GitHub repository's branch, branch_name, using
    LSST SQRE's default attributes.

    :param :class:`Repository <github3.repos.Repository>` repo: Instance
    used to protect the branch protection.
    :param str branch_name: The name of the branch.

    :returns: :class:`Protection <github3.repos.branch.Protection>` object.
    """
    branch = repo.branch(branch_name)
    if branch:
        required_status_checks = {'include_admins': True, 'strict': True,
            'contexts': ['continuous-integration/travis-ci']}
        branch.protect(required_status_checks=required_status_checks,
            enforce_admins=True)
        return branch.protection()
