S.Lott & C.A.Bowers
Let's reach way, way back. 1989 - 1990. This will let me talk about OO programming and Python Type Hints. (really) And doing OO design for things that are as pervasive (and transparent) as air. Things that need to be part of a design, but don't appear in any documentation.
The question was "Favorite Design Patterns."
This is tricky because -- well -- so many patterns appear and re-appear in software. Picking a few from the vast world of patterns is fraught with difficulties.
S.Lott & C.A.Bowers