This video demonstrates an auto-rig for snake, rope, worm or anything similar I wrote in Python-Maya.
1- Multiple seamless twist controls
2- Ability to animate the twist range for every single control.
3- No flip problem.
4- Squash stretch and ability to blend between them.
5- Ability to change the smoothness of the shape by scaling the control ( very intuitive control for smooth and hard corners. )
6- twist remaining on the control no matter where the controls are on the curve.
7- And more interesting, twist remain on the controls even after squash and stretch, and the range twist still works.