Added type annotations to pyi interface file.

MANIFEST.in

@@ -1,4 +1,4 @@
 recursive-include src/frozendict/c_src *
 include test/*
 include src/frozendict/py.typed
-include src/frozendict/frozendict.pyi
+include src/frozendict/__init__.pyi

setup.py

@@ -11,7 +11,7 @@
 readme_filename = "README.md"
 version_filename = "version.py"
 py_typed_filename = "py.typed"
-mypy_filename = "frozendict.pyi"
+mypy_filename = "__init__.pyi"
 main_url = "https://github.com/Marco-Sulla/python-frozendict"
 bug_url = "https://github.com/Marco-Sulla/python-frozendict/issues"
 author = "Marco Sulla"

src/frozendict/__init__.pyi

@@ -0,0 +1,54 @@
+from collections.abc import Hashable
+from typing import NoReturn, TypeVar, overload, Type, Optional
+
+try:
+    from typing import Mapping, Sequence, Iterable, Iterator
+except ImportError:
+    from collections.abc import Mapping, Sequence, Iterable, Iterator
+
+K = TypeVar("K")
+V = TypeVar("V")
+KV = TypeVar("KV", K, V)
+T = TypeVar("T", Mapping[K, V])
+
+class frozendict(Mapping[K, V]):
+    # Fake __init__ to describe what __new__ does:
+    @overload
+    def __init__(self, **kwargs: V) -> None: ...
+    @overload
+    def __init__(self, mapping: Mapping[K, V]) -> None: ...
+    @overload
+    def __init__(self, iterable: Iterable[Sequence[KV]]) -> None: ...
+
+    # Magic Methods:
+    def __getitem__(self, key: K) -> V: ...
+    def __len__(self) -> int: ...
+    def __iter__(self) -> Iterator[K]: ...
+    def __hash__(self) -> int: ...
+    def __repr__(self) -> str: ...
+    def copy(self: T) -> T: ...
+    def __copy__(self: T) -> T: ...
+    def __deepcopy__(self: T) -> T: ...
+    # Omit __reduce__, its used for Pickle and we don't need the annotation in code.
+    def set(self: T, key: K, value: V) -> T: ...
+    def setdefault(self: T, key: K, default: V) -> T: ...
+    def delete(self: T, key: K) -> T: ...
+    def key(self, index: int) -> K: ...
+    def value(self, index: int) -> V: ...
+    def item(self, index: int) -> Sequence[KV]: ...
+    def __or__(self: T, other: Mapping[K, V]) -> T: ...
+    def __reversed__(self) -> Iterator[K]: ...
+
+    @classmethod
+    def fromkeys(
+        cls: Type[T], 
+        seq: Iterable[K], 
+        value: Optional[V] = None
+    ) -> "frozendict[K, V]": ...
+
+    # Blacklisted methods:
+    def __setattr__(self, *a, **kw) -> NoReturn: ...
+    def __delattr__(self, *a, **kw) -> NoReturn: ...
+
+
+FrozenOrderedDict = frozendict