This matches Elems with one child. :)
If you want to match any number of children, replace the last "_" with "_*" . All part of the magic of unapplySeq. :)
As also described in the Hibernate book from King and Bauer: "With the adoption of Java™ 5 generics, the idea of a generic typesafe Data Access Object (DAO) implementation has become feasible. In this article, system architect Per Mellqvist presents a generic DAO implementation class based on Hibernate. He then shows you how to use Spring AOP introductions to add a typesafe interface to the class for query execution."
P. Talukdar, T. Brants, M. Liberman, and F. Pereira. Proceedings of the Tenth Conference on Computational Natural Language Learning (CoNLL-X), page 141--148. New York City, Association for Computational Linguistics, (June 2006)