Hi Don Knuth, author of The Art Of Computer Programming and creator of the TeX typesetting system is 83 today. Happy Birthday Don. Thank you for TeX and everything else. You're warmly invited to join me online to celebrate Don's life and work. The virtual party is on Thursday 14 January, 6:30 to 7:30pm UK time. You'll find the zoom details at (and a goto tribute) at: https://jfine2358.github.io/post/2021/01/10/happy-birthday-don-knuth/ This link also contains a discussion of how merging two binary trees provides a good example of how coroutines can be useful, as in Python's async and wait. with best wishes Jonathan