in `PUT Duplicate Email` section, there is a test code but not checking duplicate email. > Are we checking to see if an email exists before updating a user? > > Write a test: > ```python > def test_update_user(test_app, test_database, add_user): > ~SNIP~ > ``` I bring the test `test_update_user_duplicate_email` from this repo. Would you correct the Chapter 13 text?