NOTIFICATION VOLUME SLIDER

PLEASE for the love of god. Its really embarrassing that its not implemented in the first place but what got my blood boiling is that there are posts that go back SEVERAL YEARS asking for this feature.. I`m no developer but how hard can it be to implement a simple volume slider for notifications? My eardrums are exploding every time I get any kind of notification. Lowering the sound from volume mixer is not an optimal solution, because after every restart, it resets. Just get on with it already, please.