Hello, I am new to scala and spark. What does the "this.type" in set function for?
https://github.com/apache/spark/blob/481f0792944d9a77f0fe8b5e2596da1d600b9d0a/mllib/src/main/scala/org/apache/spark/mllib/optimization/GradientDescent.scala#L48 Thanks! Zhan