Macro filling_text 

macro_rules! filling_text {
    ( null ) => { ... };
    ( [$( $token:tt )*] ) => { ... };
    ( {$( $token:tt )*} ) => { ... };
    { $value:expr } => { ... };
}

Helper macro for converting types into Filling::Text. It’s used internally by the filling! and filling_list! macros.