munge_args
opts->dataset = munge_args(argc, argv, un, 3, &opts->perms);
opts->dataset = munge_args(argc, argv, un, 2, &opts->perms);
opts->dataset = munge_args(argc, argv, un, 2, &opts->perms);
opts->dataset = munge_args(argc, argv, un, 2, &opts->perms);
opts->dataset = munge_args(argc, argv, un, 3, &opts->perms);