Update add_node.py

Author: Diald

data_structures/linked_list/add_node.py

@@ -10,7 +10,7 @@ def print_LL(self): # to print the linked list
             print("The Linked List is empty ")
         else:
             n= self.head
-            while n is n ot None:
+            while n is not None:
                 print(n.data)
                 n=n.ref
     def add_begin(self,data): #to add a node in the beginning
@@ -41,4 +41,4 @@ def add_after(self,data,x):
 linked_list.add_begin(22)
 linked_list.add_after(30,11)
 linked_list.print_LL()
-#https://youtu.be/xRTdfZsAz6Y?si=EMrqVJpXjDDz1kEF
+#https://youtu.be/xRTdfZsAz6Y?si=EMrqVJpXjDDz1kEF