func (q *Deque) PopLeft() interface{} {
	return q.Items.PopLeft().Value
}
PopLeft pulls and item off the front of the deque.
package deque
import list "../linked-list"
type Deque struct {
	Items *list.List
}
func NewDeque() *Deque {
	return &Deque{Items: list.New()}
}
func (q *Deque) Append(val interface{}) {
	q.Items.Append(val)
}
func (q *Deque) Prepend(val interface{}) {
	q.Items.Prepend(val)
}
func (q *Deque) Pop() interface{} {
	return q.Items.Pop().Value
}