Add 'hi/' from commit '15db0bcdb7964ad425d6ffbdc6fefceb3928c89f'

git-subtree-dir: hi
git-subtree-mainline: 15db0bcdb7964ad425d6ffbdc6fefceb3928c89f
git-subtree-split: 15db0bcdb7964ad425d6ffbdc6fefceb3928c89f