func InitBySlice(s []int) *List {
	dummy := &Element{}
	dummy.Prev = dummy
	dummy.Next = dummy
	l := &List{dummy: dummy}
	l.PushBackSlice(s)
	return l
}
//InitBySlice returns an initialized list.

InitBySlice returns an initialized list.
// InitBySlice returns an initialized list .
func InitBySlice(s []int) *List {
	dummy := &Element{}
	dummy.Prev = dummy
	dummy.Next = dummy
	l := &List{dummy: dummy}
	l.PushBackSlice(s)
	return l
}
func InitBySlice ( s [ ] int ) * List { dummy := & Element { } dummy . Prev = dummy dummy . Next = dummy l := & List { dummy : dummy } l . PushBackSlice ( s ) return l }
InitBySlice returns an initialized list.
InitBySlice returns an initialized list .