Fix lists display call.

Change-Id: I92be8093f020276eaafb63b7fdb0e5a3f1a03a07

README.md

@@ -10,20 +10,20 @@ Cache with LFU eviction scheme implemented in Python with complexity O(1) for in
 >>> cache.insert('k1', 'v1')
 >>> cache.insert('k2', 'v2')
 >>> cache.insert('k3', 'v3')
->>> cache.display_lists()
+>>> cache
 1: ['k1', 'k2', 'k3']
 
 >>> cache.access('k2')
 'v2'
->>> cache.display_lists()
+>>> cache
 1: ['k1', 'k3']
 2: ['k2']
 
 >>> cache.get_lfu()
 ('k1', 'v1')
 
 >>> cache.delete_lfu()
->>> cache.display_lists()
+>>> cache
 1: ['k3']
 2: ['k2']
 ```