input: Write a function to implement a linked list in Python using classes. The function should include a Node class to represent a node in the linked list and a LinkedList class to represent the entire linked list. The LinkedList class should also include a method to print the list starting from the head node.
output: class Node:
      def __init__(self, data):
          self.data = data
          self.next = None
  
  class LinkedList:
      def __init__(self):
          self.head = None
  
      def print_list(self):
          temp = self.head
          while temp:
              print(temp.data, end=" ")
              temp = temp.next