actually it's not that uncommon in the wild.
research the eastern indigo snake ( I am absolutely in LOVE with it!)
they regularly eat iguanas, rattlesnakes, and other snakes, but the amazing thing is, they're completely immune to the venom of the native venomous snakes of their area!
http://users.tamuk.edu/david_hewitt/...t%20indigo.JPG
okay. I'm done.. sorry... I just adore these beauties.