Tried to make a List.>(), it doesn't work, so how do I do that?

The compiler doesn't like it- I get the error;

 expecting >, found '>>'.

But I thought a generic list could be a list of anything, even of other lists, so

  var masterList : List.<List.<whatev>>;

should be valid... I'm just not declaring it the right way?

An array of arrays seems to work fine but I need the size to vary.