func (n *Number) Half() {
	n.value /= 2
}
Half halves the value of the number.
package behavioral
type Memento struct {
	state int
}
func NewMemento(value int) *Memento {
	return &Memento{value}
}
type Number struct {
	value int
}
func NewNumber(value int) *Number {
	return &Number{value}
}
func (n *Number) Dubble() {
	n.value = 2 * n.value
}