namespaces:

using System.Collections.Generic;
using System.Linq;

using MongoDB.Bson;
using MongoDB.Bson.Serialization.Attributes;
using MongoDB.Driver;

using IAggregateFluentExtensions = MongoDB.Driver.IAggregateFluentExtensions;
using IMongoCollectionExtensions = MongoDB.Driver.IMongoCollectionExtensions;
using MongoClient = MongoDB.Driver.MongoClient;

Class used in examples:

    public class Interactions
    {
        public ObjectId Id { get; set; }
        public string ChannelId { get; set; }
        public string ContactId { get; set; }
        public string Language { get; set; }
        public List<Pages> Pages { get; set; }
        public string SiteName { get; set; }
        public int Value { get; set; }
        public int VisitPageCount { get; set; }
    }


    public class Pages
    {
        public string Url { get; set; }
        public int VisitPageIndex { get; set; }
    }