If we're on rat snakes... Our local shop has one of these in at the moment :
Japanese Ratsnake -- (Elaphe climacophora)

Beautiful green colours, maybe not as arboreal as a rough green, but the pattern of the scales is something that needs to be seen close up. I'd be tempted, but it's on the large side and I don't have room right now.

See, we may be garter folk, but we can help a little with other species.