Macro run 

macro_rules! run {
    (
        // addr is mandatory, the rest are wrapped in $(...)? to make them optional
        addr: $addr:expr
        $(, state: $state:expr )?
        $(, config: $config:expr )?
        $(, configure_app: |$app:ident| $app_body:expr )?
        $(, configure_server: |$server:ident| $server_body:expr )?
        $(,)? // Handles an optional trailing comma at the very end of the macro call
    ) => { ... };
}