Can I use IENumerable.Repeat in Unity?

 import System.Collections.Generic;
 
 var myList = List.<myClass>();
 class myClass {}
 
 var myItem = new myClass();
 myList.AddRange( IEnumerable.Repeat(myItem,2) );

gives this error: MissingMethodException: System.Collections.IEnumerable.Repeat Boo.Lang.Runtime.DynamicDispatching.MethodDispatcherFactory.ProduceExtensionDispatcher () ...