Type Alias LabelMappingHook 

pub type LabelMappingHook = Rc<dyn Fn(&str, &str, bool) -> (Option<String>, Option<String>)>;

Perl: LABEL_MAPPING_HOOK => sub { ($label, $ctr, $norefnum) => ($refnum, $id) } Returns (optional refnum string, optional id string)

Aliased Type

pub struct LabelMappingHook { /* private fields */ }