Trait Fun
Other items ingain_lep
pub trait Fun { fn invoke( &self, list: &Rc<dyn Any + 'static> ) -> Result<Rc<dyn Any + 'static>, String>; }
Fun is an extension function object.
fn invoke( &self, list: &Rc<dyn Any + 'static>) -> Result<Rc<dyn Any + 'static>, String>