Await async TaskEx

TaskEx was just an extra class which initially shipped with the CTPs of the async/await extensions for C# 5 before .NET 4.5 shipped... and is now part of the Async Targeting Pack (aka the Microsoft.Bcl.Async NuGet package) in case you want to use async/await but are targeting .NET 4.0 (which doesn't have some of the code required for it).

If you're using .NET 4.5 or later, just use Task.Run, which does the same thing. (You won't be using the targeting pack, so you won't have TaskEx.) The async targeting pack can't add a static method to the existing Task class, hence the need for TaskEx existing at all.