Angle component in Kangaroo for gridshell simulation

Hello,

I am a bit new to Kangaroo. I came accross the Gridshell example file in K2Eng which is super awsome and I would like to thank format engineers for this !!

I was unable to understand the angle component in the script. It would be very kind if someone could explain me the logic behind the assigning of line A and line B and how the bending works because of the particular method of assigning

Thanks

Gridshell.gh