person1.cs

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public string FullName => FirstName + " " + LastName;

    public static Person operator +(Person person1, Person person2) => person1;

    public string this[int i] => "Hi";

    public void Hello() => Console.WriteLine("Hello");
}