class Node:
    def __init__(self, value):
        self.value = value
        self.next = None


class LinkedList():
    def __init__(self):
        self.head = None

    def append(self, value):
        if self.head is None:
            self.head = Node(value)
            return
        node = self.head
        while node.next:
            node = node.next
        node.next = Node(value)
        return

    def to_list(self):
        mylist = []
        if self.head is None:
            return
        node = self.head
        while node:
            mylist.append(node.value)
            node = node.next
        return mylist


# Test your method here
linked_list = LinkedList()
linked_list.append(3)
linked_list.append(2)
linked_list.append(-1)
linked_list.append(0.2)

print ("Pass" if  (linked_list.to_list() == [3, 2, -1, 0.2]) else "Fail")


class DoubleNode:
    def __init__(self, value):
        self.value = value
        self.next = None
        self.previous = None


class DoublyLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def append(self, data):
        if self.head is None:
            self.head = DoubleNode(data)
            self.tail = self.head
            return
        else:
            newnode = DoubleNode(data)
            self.tail.next = newnode
            newnode.previous = self.tail
            self.tail = newnode
            return


# Test your class here

linked_list = DoublyLinkedList()
linked_list.append(1)
linked_list.append(-2)
linked_list.append(4)

print("Going forward through the list, should print 1, -2, 4")
node = linked_list.head
while node:
    print(node.value)
    node = node.next

print("\nGoing backward through the list, should print 4, -2, 1")
node = linked_list.tail
while node:
    print(node.value)
    node = node.previous