[Isolated] testing method

Hi everyone. Hey I am new to TypeMock and learning it for my boss and team. I am trying to write a test with a beginning setup like:
[TestMethod]
[Isolated]
public class MyMethodTest
{
...
}
What "using ...;" reference statement do need to use the [Isolated] and Isolate.<something> method and classes. Right now with the [Isolated] attribute written, VS tells me that "Cannot resolve symbol 'Isolated' "?