+ (match idx {
+ // Unknown bits are even bits which we don't understand, we list ones which we do
+ // here:
+ // unknown, upfront_shutdown_script, unknown (actually initial_routing_sync, but it
+ // is only valid as an optional feature), and data_loss_protect:
+ 0 => (byte & 0b01000100),
+ // unknown, unknown, unknown, var_onion_optin:
+ 1 => (byte & 0b01010100),
+ // fallback, all even bits set:
+ _ => (byte & 0b01010101),
+ }) != 0