This takes me back more than 20 years when I first started to use Putty and learnt about Simon Tatham, and incidentally I learnt about coroutines at the same ti

This takes me back more than 20 years when I first started to use Putty and learnt about Simon Tatham, and incidentally I learnt about coroutines at the same time from another source and later learned that PuTTY used them!