opt_flag
if ((r = opt_flag("restrict", 0, &opts)) != -1) {
} else if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {
} else if ((r = opt_flag("port-forwarding", 1, &opts)) != -1) {
} else if ((r = opt_flag("agent-forwarding", 1, &opts)) != -1) {
} else if ((r = opt_flag("x11-forwarding", 1, &opts)) != -1) {
} else if ((r = opt_flag("touch-required", 1, &opts)) != -1) {
} else if ((r = opt_flag("verify-required", 1, &opts)) != -1) {
} else if ((r = opt_flag("pty", 1, &opts)) != -1) {
} else if ((r = opt_flag("user-rc", 1, &opts)) != -1) {
int opt_flag(const char *opt, int allow_negate, const char **optsp);
if ((r = opt_flag("cert-authority", 0, &opts)) != -1) {