Either, Left, Right
LinksLinks
Daniel Westheide 
The Neophyte's Guide to Scala Part 7: The Either Type
http://danielwestheide.com/blog/2013/01/02/the-neophytes-guide-to-scala-part-7-the-either-type.html
API Dokumentation:
Either (Class)
Either (Object)
Left (Class)
Right (Class)