Is it possible to aggregate through realm app?

Hi everyone i’m trying that should remove all the duplicates but it returns uncaught promise rejection: TypeError, am I doin something wrong or it is just not possible? Here’s the code
exports = function(payload, response) {
const mongodb = context.services.get(“mongodb-atlas”);
//var oggetti=EJSON.parse(payload.body.text())
//var inserimentoDB = mongodb.db(“tesi”).collection(“cookies”).insertMany(oggetti)
const pipeline=[
{ $group: {
_id: { ‘Valore’: ‘$Valore’ },
dups: { ‘addToSet': '_id’ },
count: { ‘$sum’: 1 }
}},
{ ‘$match’: { count: { ‘$gt’: 1 } }}
]
mongodb.db(“tesi”).collection(“cookies”).aggregate(pipeline).toArray().then(docs => docs.forEach(function (doc){
doc.dups.shift();
mongodb.db(“tesi”).collection(“cookies”).dups.delete({
_id:{$in: doc.dups}
})
}))
}