How to obtain Variant underlying type?

[anonymouse via Digitalmars-d-learn]

std.variant;
Variant v = [[1], [2], [3]];

writeln(v.type); // int[][]
typeof(v.type); // TypeInfo
assert(v.type == typeid(int[][]);
As demonstrated by the assert statement, .type returns the typeid 
of the underlying type. How would I obtain the actual type such 
that:

     auto vb = v.base; // what should I put here to achieve the 
following:
     typeof(vb); // int[][]
     assert(vb == [[1], [2], [3]]);

--anonymouse