Use with statement where it improves the documentation (closes #10461)
diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index b6ab342..42c867d 100644
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -512,7 +512,8 @@
 
    def tail(filename, n=10):
        'Return the last n lines of a file'
-       return deque(open(filename), n)
+       with open(filename) as f:
+           return deque(f, n)
 
 Another approach to using deques is to maintain a sequence of recently
 added elements by appending to the right and popping to the left::