def append(self, data):
    node = Node(data)
    currentNode = self.head
    while (currentNode.next is not None):
        currentNode = currentNode.next
    currentNode.next = node
def append(self, data):
    node = Node(data)
    currentNode = self.head
    while (currentNode.next is not None):
        currentNode = currentNode.next
    currentNode.next = node