Trait Watcher
casbin
pub trait Watcher: Send + Sync { fn set_update_callback(&mut self, cb: Box<dyn FnMut() + Send + Sync>); fn update(&mut self, d: Option<EventData>); }
fn set_update_callback(&mut self, cb: Box<dyn FnMut() + Send + Sync>)
fn update(&mut self, d: Option<EventData>)