Macro export_app 

macro_rules! export_app {
    ($register:path) => { ... };
}

Export register, a fn(&mut Registry) -> BridgeResult<()>, as the application’s entry point.

Invoke once in the application crate, as ccf_app::export_app!(register);. If register returns an error or panics, CCF fails to initialize the application. The macro also keeps panic messages from application code, which may contain confidential data, out of node output.