Update surname

updateSurname.swift

let actor = Actor(name: "George", surname: "Clooney")
let movie = Movie(title: "A beautiful movie", year: "2010", actors: [actor])
print(movie.actors) // [George Clooney]
print(movie.title)  // A beautiful movie

let surnameLens = Movie.Lenses.mainActor >>> Actor.Lenses.surname
let updatedMovie = surnameLens.set(movie, "Pitt")

print(updatedMovie.actors) // [Brad Pitt, George Clooney]
print(updatedMovie.title)  // A beautiful movie
print(Movie.Lenses.mainActor.get(updatedMovie)) // [Brad Pitt]