Use range() rather than xrange().

This would be a bit less efficient in Python 2.7, but it would work on Python 3.x.

examples/benchmark.py

@@ -35,7 +35,7 @@ def run_benchmark(sess):
     proc.start()
 
     start = datetime.now()
-    for i in xrange(0, 1000):
+    for i in range(0, 1000):
         sess.get(URL)
         sys.stdout.write(".")
     end = datetime.now()