I remember many of them from germany. As small vans, for maybe 6 to 8 people. As delivery cars, used by handyman/tradespeople/landscapers/gardeners, utility/cleaner cars driving through parks, car-free downtown/CBD, and so on. Until about a decade ago.
Nowadays I'm only visiting, and the picture seems to have changed somehow, they are still there, but less so. Most recently grocery deliveries by http://picnic.de come to mind. Don't know which brand/model that car is, but it looks 'Kei' to me.
Plenty of people export them, annoyingly for Japanese , this drives up the prices on second hand vehicles…what’s supposed to be a cheap inexpensive cars becomes a delicacy in the US lol
To me "property based testing" would come to mind, where you would define properties of the input and output of a method and the library runs random test cases for you.
The most prominent implementation would be QuickCheck[0], which is written in Haskell, but there are re-implementations of it in almost every language.
