[AdieuToLogic]

> Their usage of upsert appears different than I was used to: > Them: Upsert = Get or Insert

I agree that their choice of labeling the proposal as "upsert" is less than ideal. However, this functionality is reminiscent of a very useful Perl capability known as autovivification[0] as described in the motivation section:

  A common problem when using a Map or WeakMap is how to 
  handle doing an update when you're not sure if the key 
  already exists in the map.

0 - https://en.wikipedia.org/wiki/Autovivification