// add add a node to tail of a list.
add add a node to tail of a list.
// add add a node to tail of a list .
func (l *list) add(newn *node) {
	if l.head == nil {
		l.head = newn
		newn.next = nil
		return
	}
	for n := l.head; n != nil; n = n.next {
		if n.next == nil {
			n.next = newn
			return
		}
	}
	return
}
func ( l * list ) add ( newn * node ) { if l . head == nil { l . head = newn newn . next = nil return } for n := l . head ; n != nil ; n = n . next { if n . next == nil { n . next = newn return } } return }
add add a node to tail of a list.
add add a node to tail of a list .
// sequential access