The `AllInstances` using in the `MS Fakes`

MS Visual Studio 2015 Enterprise.

From MSDN:

To use a shim for an instance method, write AllInstances between the type name and the method name:

System.IO.Fakes.ShimFile.AllInstances.ReadToEnd = ...

But when I write . after ShimFile the IntelliSense has not AllInstances item in the combobox:

Also I try to do the same for DateTime and I see other problem: the AllInstances is exists, but the IntelliSense has not items for it:

Why does it happen?