Update

Author: Sonawane-Karan26

Chapter04/append_at_any_location_singly_linkedlist.py

@@ -7,6 +7,7 @@ def __init__(self, data=None):
 
 class SinglyLinkedList:
     def __init__ (self):
+        self.tail = None
         self.head = None
         self.size = 0