Here is the linked_list.py provided in the lesson. They never instantiate Node() in the LinkedList() how are they able to use the methods from Node()?

```
class Node:
def __init__(self, value):
self.value = value
self.next_node = None
def get_value(self):
return self.value
def get_next_node(self):
return self.next_node
def set_next_node(self, next_node):
self.next_node = next_node
class LinkedList:
def __init__(self, head_node=None):
self.head_node = head_node
def insert(self, new_node):
current_node = self.head_node
if not current_node:
self.head_node = new_node
while(current_node):
next_node = current_node.get_next_node()
if not next_node:
current_node.set_next_node(new_node)
current_node = next_node
def __iter__(self):
current_node = self.head_node
while(current_node):
yield current_node.get_value()
current_node = current_node.get_next_node()
```