[Go][excerpt] list push

// Excerpt
// Push data into the tail of the list
func (list *List) Push(data interface{}) {
    node := node{data: data, next: nil, prev: nil}
    if list.head == nil {
        list.head = &node
        list.tail = &node
    } else {
        list.tail.next = &node
        node.prev = list.tail
        list.tail = &node
    }
}