In the example where you `git checkout -b feature_x`, I believe you also want to `git merge feature_x` after you `git checkout master`, as the `-d` flag on `git

In the example where you `git checkout -b feature_x`, I believe you also want to `git merge feature_x` after you `git checkout master`, as the `-d` flag on `git branch -d feature_x` will only delete the branch if it's been merged.