This is a very good article about the var keyword in C#:
http://jeremybytes.blogspot.hu/2014/02/demystifying-var-keyword-in-c.html

Recently I started to implement UI tests for a WPF application with White. I’m entirely new to WPF, so it wasn’t obvious to me how can I set the AutomationId of a TreeViewItem which is generated during runtime based on the contained object’s property. Here’s the solution: