The package in question is iterable. The spago registry search iterable reports its existence in the package set, but actually adding the said package to the spago.yaml and building the project result in an error:
The following packages do not exist in your package set:
- iterable
The spago version is the latest 0.93.9 and the spago.yaml is the minimum one after spago init. It also contradicts the result of its own spago ls packages command, which reports no such package.