I get what Nano is and how it works. Every account has its own blockchain, the send/receive blocks, and all that. It's incredible really.
I've looked at the Bitcoin code a lot over the years and it's absolutely so insanely complex. Change one thing and it can have crazy downstream effects on many other parts of the code, especially the consensus stuff.
My question is: How the hell did Colin actually code Nano? Did he start with another cryptocurrency (Bitcoin??), then alter it? Or was it created from scratch? How do you test something like this when you're one person? I'm a programmer and it blows my mind that someone built this without any help.