{
        "users": [
            {
                "first": "Homer",
                "last": "Simpson"
            },
            [
                2,
                "Hank",
                "Hill"
            ],
            [
                0,
                2,
                "Peter",
                "Griffin"
            ]
        ]
    }

There was a tester linked from the site. Looks like he added the [0, to handle that case.