http://blog.nilsjonsson.com/post/632748350/never-declare-another-csharp-delegate-again

Nightclub.cs

using System;
using System.Collections.Generic;

class Nightclub
{
    private readonly List<Person> occupants = new List<Person>();
    
    public Nightclub()
    {
        occupants = new List<Person>();
    }
    
    public Func<Person, bool> Bouncer { get; set; }
    
    public Person[] Occupants
    {
        get { return occupants.ToArray(); }
    }
    
    public bool Enter(Person person)
    {
        if ((Bouncer != null) && !Bouncer(person)) return false;
        occupants.Add(person);
        return true;
    }
}