Giving non-leaf nodes data/values in protovis

Question

My data looks similar to this:

var root = {
    node1: {
        node2: 4,
        node3: 2
    },
    node4: {
        node5: 3
    }
};

Which is similar to how they suggest the data be laid out for tree structures in their examples. My question is this: how would I give values to node1 and node4?

Thanks.