chore(types): add type hints to meiga decorator (#27)

meiga/decorators/meiga_decorator.py

@@ -1,13 +1,23 @@
+from functools import wraps
+from typing import Callable, TypeVar, cast
+
+from typing_extensions import ParamSpec
+
 from meiga.alias import Failure
 from meiga.decorators.unexpected_decoration_order_error import (
     UnexpectedDecorationOrderError,
 )
 from meiga.error import Error
 from meiga.on_failure_exception import OnFailureException
+from meiga.result import Result
+
+P = ParamSpec("P")
+R = TypeVar("R", bound=Result)
 
 
-def meiga(func):
-    def _meiga(*args, **kwargs):
+def meiga(func: Callable[P, R]) -> Callable[P, R]:
+    @wraps(func)
+    def _meiga(*args: P.args, **kwargs: P.kwargs) -> R:
         try:
             if isinstance(func, staticmethod):
                 return Failure(UnexpectedDecorationOrderError())
@@ -18,6 +28,6 @@ def _meiga(*args, **kwargs):
         except OnFailureException as exc:
             return exc.result
         except Error as error:
-            return Failure(error)
+            return cast(R, Failure(error))
 
     return _meiga