Connections - Can someone please explain how these work?

[atomsinthevoid]

Ok so after diving deep into the train example I finally isolated the code that figures out if the junction should be used or not.  I feel like I'm in the brain of a madman here but it's starting to make a bit of sense.  I'm still somewhat new to C# but I do get the hang of things quickly.  That said, perhaps you can help me make sense of this line of code that I found in the TrainCarManager.cs file:

Code:

       
void OnCPReached(CurvySplineMoveEventArgs e)
       {
           var jc = e.ControlPoint.GetMetadata<MDJunctionControl>();
           if (jc)
           {
               if (jc.UseJunction)
               {
                   e.Follow(e.ControlPoint.Connection.OtherControlPoints(e.ControlPoint)[0]);
                   // Set the controller to use the new spline
                   SplineController controller = (SplineController)e.Sender;
                   controller.Spline = e.Spline;
                   controller.RelativePosition = e.TF;
               }
           }
       }

So, I get that this is an event listener, and I notice that it's attached to the Spline controller of each car above via this method:

Code:

        void setController(SplineController c, CurvySpline spline, float speed)
        {
            c.Spline = spline;
            c.Speed = speed;
            c.OnControlPointReached.AddListenerOnce(OnCPReached); // RIGHT HERE
            c.OnEndReached.AddListenerOnce(CurvyDefaultEventHandler.UseFollowUpStatic);
        }

Cool.  So every control point is going to call "OnCPReached"..  Then I notice there's some metadata added on the junction which is just a bool toggle on or off, so let's not worry too much about that.  

What I want to know is what are each of these lines doing?  Especially that e.Follow one.  Of course, I know it's telling the connection to follow the "other" control point, and somehow e.ControlPoint will tell it to follow the other connection.  But how does it know that?!  I notice the [0] at the end there, is this an array?

                   e.Follow(e.ControlPoint.Connection.OtherControlPoints(e.ControlPoint)[0]);
                   // Set the controller to use the new spline
                   SplineController controller = (SplineController)e.Sender;
                   controller.Spline = e.Spline;
                   controller.RelativePosition = e.TF;

At a high level I get what's happening here, but I'd like to understand it more fundamentally since I plan to adapt this idea to my own purposes and I can't really do that until I look under the hood a bit more.

Thanks for the help!