about add_watch_callback

Use the add_watch_callback function to listen key events. If the key is deleted, how to get the value before the key deleted in the callback function of add_watch_callback.
For example:
key：/hello value：1234
delete /hello
Using add_watch_callback how to get 1234 when delete event occurs

Looking forward to your answer, thank you very much

Start by reading the add_watch_callback API and the watch-event handling in python-etcd3. Check the deletion event data for the /hello example and determine whether the prior value is exposed. Done means documenting the supported way to retrieve 1234, or clearly stating that the callback cannot provide it.

Written by the indexing model from the issue text.