input: Write a function to implement a linked list using classes in Python. Create a Node class to represent the node in a linked list and a LinkedList class to represent the entire linked list. The LinkedList class should have methods to print the entire list. If the list is empty, the output should be nothing.
  
  class Node:
      """Node class to represent the node in a linked list"""
      def __init__(self, data):
          self.data = data
          self.next = None
  
  class LinkedList:
      """LinkedList class to represent the entire linked list"""
      def __init__(self):
          self.head = None
      
      def print_list(self):
          node = self.head
          while(node):
              print(node.data)
              node = node.next
  
  assert LinkedList().print_list()==None
  
  node1 = Node(1)
  node2 = Node(2)
  node3 = Node(3)
  
  linked_list = LinkedList()
  linked_list.head = node1
  node1.next = node2
  node2.next = node3
  
  assert linked_list.print_list()==None
output: def print_list(self):
      node = self.head
      while node:
          print(node.data)
          node = node.next