public bool Delete(dynamic lookup)
{
var _qs = lookup.ids as string;
string query = String.Concat("{ \"_id\":", "{ \"$in\": " + _qs + " } }");
var _query = new QueryDocument(BsonSerializer.Deserialize<BsonDocument>(query));
var _coll = _db.GetCollection(lookup.collection.ToString());
_coll.Remove(_query);
return true;
}