Green tree python or emerald tree boa! Also, not at all "viper-like". Most of the ETB's bad rep is because most are wild caught animals. Captive bred ETB are more or less just like captive bred GTP in temperament.
It's true that they're more display animals and usually don't tolerate handling like how BCI or ball pythons do, but CBB animals can still be handled safely (during the day), just tend to be more nervous.
If you're interested, totally start some research and see if you like them! This site has all the info you need to read up on GTP's to start out. http://moreliaviridis.yuku.com/forum...dry-The-Basics