Function hook 

pub fn hook<F>(f: F) -> ExecHook
where
    F: for<'a> Fn(&'a dyn Executor) -> ExecFuture<'a, Result<(), ExecError>> + Send + Sync + 'static,

Wrap a closure as an ExecHook. The named-function-plus-Box::pin shape generated code uses:

q.add_hook(hook(|db| Box::pin(async move { … })));