Implement doubly-linked list with O(1) operations

Author: RahwaZeslusHaile

Sprint-2/implement_linked_list/linked_list.py

@@ -12,7 +12,6 @@ def __init__(self):
 
     def push_head(self, value):
         new_node = Node(value)
-        
         if self.head is None:
             self.head = new_node
             self.tail = new_node
@@ -24,6 +23,7 @@ def push_head(self, value):
         return new_node
 
     def pop_tail(self):
+       
         if self.tail is None:
             raise IndexError("pop_tail from empty linked list")