How to define callbacks in version V2.x.x

[Ksm125]

I try to define a callbacks around deliver but i could not figure out how to do it now.
Before, on the version v.1.x.x, we could just define (and it was documented on the readme).

before_deliver do 
# do something
end

But now i do not see anywhere, without writting a custom DevlieryMethod.
For usage to have something, for example, i could mark a record sent_at when the notification has been sent after the delivery was called