과제-더블 링크드리스트 prepend

def prepend(self,data):

	new_node = Node(data)

    if self.head is None:
        self.head = new_node
        self.tail = new_node
    else: 
        new_node.next = self.head
        self.head.prev = new_node
        self.head = new_node
        
my_list.prepend(2)
my_list.prepend(3)
my_list.prepend(5)
my_list.prepend(7)

print(my_list) = 2 3 5 7
print(my_list.head.data) = 2
print(my_list.tail.data) = 7