MongoDB で埋め込み配列フィールドをソートするにはどうすればよいですか?

db.students.aggregate([
    // Initial document match
    { $match: {
        _id : 1
    }},
    // Expand scores array
    { $unwind: '$scores' },
    // Filter homework scores
    { $match: {
        'scores.type': 'homework'
    }},
    // Sort in descending order
    { $sort: {
        'scores.score': -1
    }}
])

{
    "result" : [
        {
            "_id" : 1,
            "name" : "Aurelia Menendez",
            "scores" : {
                "type" : "homework",
                "score" : 71.76133439165544
            }
        },
        {
            "_id" : 1,
            "name" : "Aurelia Menendez",
            "scores" : {
                "type" : "homework",
                "score" : 34.85718117893772
            }
        }
    ],
    "ok" : 1
}