同一个处理器添加两次、移除一次后，这段程序会输出什么？

using System;

var signal = new Signal();
EventHandler handler = (_, _) => Console.WriteLine("called");

signal.Changed += handler;
signal.Changed += handler;
signal.Changed -= handler;
signal.Raise();

public sealed class Signal
{
    public event EventHandler? Changed;
    public void Raise() => Changed?.Invoke(this, EventArgs.Empty);
}