BOND_OPT_MODE
valptr = bond_opt_parse(bond_opt_get(BOND_OPT_MODE), &newval);
err = __bond_opt_set(bond, BOND_OPT_MODE, &newval,
[BOND_OPT_MODE] = {
.id = BOND_OPT_MODE,
modeval = bond_opt_get_val(BOND_OPT_MODE, params->mode);
val = bond_opt_get_val(BOND_OPT_MODE, BOND_MODE(bond));