I had never seen nor heard of these in my life before. Then one day last week I saw two of them in Boston. And they weren't affiliated with each other, they looked totally different and were obviously separate businesses. Is this a thing? Are they new? Do they have them in other cities? Have they been here all along and I've just missed them? And if that's the case, how did I see two in one day?! And neither one was parked and open for business, they were both on the move, and during the middle of the day on a Tuesday no less. What's going on?