Macro tx_meta_data 

macro_rules! tx_meta_data {
    ($len:expr; $($item:expr),+ $(,)?) => { ... };
    ($($item:expr),+ $(,)?) => { ... };
}

Concatenates multiple TX metadata sources into a single array of trait objects.

Accepts any combination of single transmitters or transmitter bundles. Enforces that the resulting trait objects implement TxMetaDataProvider.