added deque data structure

data_structures.py

@@ -0,0 +1,24 @@
+#! /usr/bin/env python3
+
+"""
+	python3 has many standards data strctures inbuilt and sometimes these are very useful.
+"""
+
+
+#deque -> doubly ended queue.
+
+#insertion and removal operations are faster.
+# deque -> remove O(1)
+# python list -> remove O(n)
+
+from collections import deque
+q = deque()
+
+q.append('eat')
+q.append('sleep')
+q.append('code')
+
+q   # output -> deque(['eat', 'sleep', 'code'])
+
+q.popleft() # deque -> ['sleep', 'code']
+