Fix typo (lets -> let's)

diff --git a/python/testing.md b/python/testing.md
index d4911ef4d349ace0f32756ffa139171a8371a64b..4965b669b1f3540255cbc57385877f689bafd3e0 100644 (file)
--- a/python/testing.md
+++ b/python/testing.md
@@ -256,7 +256,7 @@ our test suite again.
 Making a Standalone Script
 --------------------------
 
-Now that our module has been tested, lets turn this program into a standalone 
+Now that our module has been tested, let's turn this program into a standalone 
 script that we can run from the command line. This takes very little additional 
 work, now that we have our function in a module.