Option to filter/mask notifications

[diggit]

Is your feature request related to a problem? Please describe.
There are applications, which produce notifications and I am not interested in those. Is is not possible to turn notification at the source.
I used dunst in past and it had a way of filtering out of notifications. Similar to what scripting in swaync does, but it was possible to do some action on notification without external script.

Describe the solution you'd like
Same way as in scripting matches notification to script, I would like to have an option to alter/mask out the notification.

Describe alternatives you've considered
Disabling notification at the source app - not accepted by author.