@startuml

interface Displayable {
	+ Display(): void
}

class Library {
	- items: []Displayable
	+ NewLibrary(): Library
	+ AddItem(item: Displayable): void
	+ DisplayItems(): void
}

package "items" {
	class Magazine {
		- Title: string
		- PublishedAt: string
		+ NewMagazine(t: string, p: string): Magazine
		+ Display(): void
	}

	class Book {
		- Title: string
		- Author: string
		+ NewBook(t: string, a: string): Book
		+ Display(): void
	}
}

Book ..|> Displayable
Magazine ..|> Displayable
Library ..> Displayable : uses

@enduml