What is GrooveJoint2D used for, and how do you use it?

:information_source: Attention Topic was automatically imported from the old Question2Answer platform.
:bust_in_silhouette: Asked By JTJonny
:warning: Old Version Published before Godot 3 was released.

It seems to do nothing. I assigned its A and B node to two RigidBody2Ds, then changed the length and initial_offset in code , but nothing seems to change.