I do actually. My last job had a mainframe team maintaining (and adding to) an AS/400 application. They still had punchcard programs. They had json apis. Each

I do actually. My last job had a mainframe team maintaining (and adding to) an AS/400 application. They still had punchcard programs. They had json apis. Each one had some variation on parsing http from a raw tcp connection with IBM RPG. I had to do some unspeakable things to a ruby library so I could control the order of the headers.