func (d *Directory) Child() []Component {
	return d.childs
}
Child returns child elements.
package composite
type Component interface {
	Add(child Component)
	Name() string
	Child() []Component
	Print(prefix string) string
}
type Directory struct {
	name   string
	childs []Component
}
func (d *Directory) Add(child Component) {
	d.childs = append(d.childs, child)
}
func (d *Directory) Name() string {
	return d.name
}