Macro flow 

macro_rules! flow {
    (log $n:ident: $($x:tt)*) => { ... };
    ($($x:tt)*) => { ... };
}

Breaks the control-flow if the block returns a value for which ConsumedEvent::is_consumed is true.

It does the classic into()-conversion and returns the result.

The difference to try_flow is that this on doesn’t Ok-wrap the result.

Extras: If you add a marker as in flow!(log ident: {...}); the result of the operation is written to the log.