feat: added type annotation

CHANGES.md

@@ -3,6 +3,8 @@
 
 ### Release 0.1.2 (unreleased)
 
+- Added type annotations.
+
 #### Testing
 
 - Test under python 3.10, 3.11, and 3.12.

MANIFEST.in

@@ -5,4 +5,5 @@ prune .github
 # these are redundant, as setuptools-scm includes everything in the git repo
 include LICENSE.txt README.md CHANGES.md
 include tox.ini
+include src/unflatten.pyi src/py.typed
 recursive-include tests *.py

src/unflatten.pyi

@@ -0,0 +1,16 @@
+from typing import Mapping
+from typing import overload
+from typing import Sequence
+from typing import TypeAlias
+from typing import TypeVar
+
+_T = TypeVar("_T")
+
+Unflattened: TypeAlias = dict[
+    str, _T | "Unflattened[_T]" | list[_T | "Unflattened[_T]"]
+]
+
+@overload
+def unflatten(arg: Mapping[str, _T]) -> Unflattened[_T]: ...
+@overload
+def unflatten(arg: Sequence[tuple[str, _T]]) -> Unflattened[_T]: ...