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@@ -30,3 +30,14 @@ Design of our to-do list app:
 * View a list: use GET request. (It's a normal browser visit to the page)
 * Create a brand new list: a special URL will accept POST requests `lists/new`
 * Add new item to list: have a separate URL to send POST requests `/lists/<list identifier>/add_item`
+
+## 7.2 Implementing the New Design Incrementally Using TDD
+
+![Implementing New Design using TDD](img/7-1.jpg)
+
+* On top-level, adding new feature by:
+  * 1. new FT
+  * 2. New app code
+  * 3. Refactor code
+* On UT level:
+  * Add/Modify tests to verify changes we make
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