MongoDB aggregate and functions

[YongGopher (YoungGopher)]

Hello
I have basic code to delete duplicates from collection in mongodb

db.myCollection.aggregate([
 {
        "$group": {
            "_id": {"key": "$key"},
            "dups": {"$push": "$_id"},
            "count": { "$sum": 1 }
        }
    },
    {
         "$match": {
             "count": { "$gt": 1 }
         }
     }
    ]).forEach(function(doc){
        doc.dups.shift();
        db.myCollection.remove({
            "_id" : {"$in": doc.dups}
        });
    })

But how all of this execute using library mgo?

go-mgo/mgo

I’ve see examples with Pipe (for sorting and grouping) but how use “forEach” function in mgo
Did someone execute something like this?
Thanks!