Macro cycle_error_handling 

macro_rules! cycle_error_handling {
    ([]) => { ... };
    ([(cycle_fatal) $($rest:tt)*]) => { ... };
    ([(cycle_stash) $($rest:tt)*]) => { ... };
    ([(cycle_delay_bug) $($rest:tt)*]) => { ... };
    ([$other:tt $($modifiers:tt)*]) => { ... };
}