Usually a method defined in an interface contains no code and thus cannot itself be called; it must be implemented by non-abstract code to be run when it is invoked. An interface called "codice_1" might define two methods: codice_2 and codice_3. It can be implemented in different ways, for example, codice_4 and codice_5—the first being fast, working with a data structure of fixed size, and the second using a data structure that can be resized, but at the cost of somewhat lower speed.