async Task Main()
{
	var client = new MongoClient();
	var db = client.GetDatabase("polymorphismTest");
	var col = db.GetCollection<IFoo>("iFoo");
	
	// Clean up any existing documents
	await col.DeleteManyAsync(Builders<IFoo>.Filter.Empty);
	
	// Insert 2 new test documents of different types, each implementing IFoo
	await col.InsertOneAsync(new Widget1() { Id = ObjectId.GenerateNewId(), SomeField = "ABC", Bar = 10 });
	await col.InsertOneAsync(new Widget2() { Id = ObjectId.GenerateNewId(), SomeField = "ABC", Bar = 10M });
	
	// Build a query using .OfType<> on the collection.
	var widget1QueryColOfType = col.OfType<Widget1>().Find(Builders<Widget1>.Filter.Eq(x => x.SomeField, "ABC"));
	var widget2QueryColOfType = col.OfType<Widget2>().Find(Builders<Widget2>.Filter.Eq(x => x.SomeField, "ABC"));
	Console.WriteLine("OfType<> on the Collection");
	Console.WriteLine(widget1QueryColOfType.ToString());
	Console.WriteLine(widget2QueryColOfType.ToString());
	Console.WriteLine();
	
	// Build a query using .OfType<> on the Builder to change from IFoo to the concrete type.
	var widget1QueryBuilderOfType = col.Find(Builders<IFoo>.Filter.OfType<Widget1>(Builders<Widget1>.Filter.Eq(x => x.SomeField, "ABC")));
	var widget2QueryBuilderOfType = col.Find(Builders<IFoo>.Filter.OfType<Widget2>(Builders<Widget2>.Filter.Eq(x => x.SomeField, "ABC")));
	Console.WriteLine("OfType<> on the Builder");
	Console.WriteLine(widget1QueryBuilderOfType.ToString());
	Console.WriteLine(widget2QueryBuilderOfType.ToString());
	Console.WriteLine();
	
	Console.WriteLine("Documents in the database");
	var rawDocsInDatabase = await db.GetCollection<BsonDocument>("iFoo").Find(Builders<BsonDocument>.Filter.Empty).ToListAsync();
	foreach(var doc in rawDocsInDatabase)
		Console.WriteLine(doc.ToJson());
}

public interface IFoo
{
	ObjectId Id { get; set;}
	string SomeField { get; set;}
}

public class Widget1 : IFoo
{
	public ObjectId Id {get;set;}
	public string SomeField { get; set; }
	public int Bar { get; set; }
}

public class Widget2 : IFoo
{
	public ObjectId Id {get;set;}
	public string SomeField { get; set; }
	public Decimal Bar { get; set; } 
}