def METHOD_NAME(branch, force=False):
    """ Checkout a git branch.
        :param str branch: Name of branch, should not currently exist.
    """
    command = [ 'git', 'checkout', branch ]
    if force:
        command.append('-f')
    (_stdoutdata, _stderrdata, ret) = run_command(command)
    if ret != 0:
        raise RuntimeError("failed to check out branch %s" % branch)