psf/black code formatting (#1277)

data_structures/queue/double_ended_queue.py

@@ -5,11 +5,11 @@
 import collections
 
 # initializing deque
-de = collections.deque([1, 2, 3,])
+de = collections.deque([1, 2, 3])
 
 # using extend() to add numbers to right end
 # adds 4,5,6 to right end
-de.extend([4,5,6])
+de.extend([4, 5, 6])
 
 # printing modified deque
 print("The deque after extending deque at end is : ")
@@ -17,7 +17,7 @@ print(de)
 
 # using extendleft() to add numbers to left end
 # adds 7,8,9 to right end
-de.extendleft([7,8,9])
+de.extendleft([7, 8, 9])
 
 # printing modified deque
 print("The deque after extending deque at beginning is : ")