Macro convert_all 

macro_rules! convert_all {
    ($err:expr, $( $item:expr ),* $(,)?) => { ... };
}

A macro that tries to convert each provided item into a type. If any of the conversions fail, it short-circuits and returns the error.

The first argument $err is a closure that accepts an error and returns a SubtrActorResult. It is used to map any conversion errors into a SubtrActorResult.

Subsequent arguments should be expressions that implement the TryInto trait, with the type they’re being converted into being the one used in the Ok variant of the return value.