using System;

using System.Linq;

using System.Collections.Generic;

using LinqKit;

using System.Linq.Expressions;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        List<Session> sessions = new();

        var predicate = GetPredicate();

        predicate.And(s => s.username.Contains("test"));

        Console.WriteLine(predicate.ToString());

        var predicate2 = GetPredicateAsStarter();

        predicate2.And(s => s.username.Contains("test"));

        Console.WriteLine(predicate2.ToString());

    }

    public static Expression<Func<Session, bool>> GetPredicate() => PredicateBuilder.New<Session>().Start(s => s.active);

    public static ExpressionStarter<Session> GetPredicateAsStarter() => PredicateBuilder.New<Session>().Start(s => s.active);

}

​

public record Session(bool active, string username);