diff --git a/generate_async_version.py b/generate_async_version.py
index 19d247b..68f6b57 100644
--- a/generate_async_version.py
+++ b/generate_async_version.py
@@ -69,14 +69,8 @@ def gen_client(output_client_filename):
         code = code.replace(f'self.{method}(', f'await self.{method}(')
 
     # specific cases
-    code = code.replace(
-        'self.users_playlists_change(',
-        'await self.users_playlists_change('
-    )
-    code = code.replace(
-        'self.rotor_station_feedback(',
-        'await self.rotor_station_feedback('
-    )
+    code = code.replace('self.users_playlists_change(', 'await self.users_playlists_change(')
+    code = code.replace('self.rotor_station_feedback(', 'await self.rotor_station_feedback(')
     code = code.replace('return DownloadInfo.de_list', 'return await DownloadInfo.de_list_async')
 
     code = DISCLAIMER + code
diff --git a/yandex_music/client.py b/yandex_music/client.py
index 5542a16..2f7027d 100644
--- a/yandex_music/client.py
+++ b/yandex_music/client.py
@@ -1,7 +1,7 @@
 import functools
 import logging
 from datetime import datetime
-from typing import Dict, List, Optional, Union
+from typing import Dict, List, Optional, Union, TypeVar, Callable, Any
 
 from yandex_music import (
     Album,
@@ -55,12 +55,14 @@ de_list = {
 
 logging.getLogger(__name__).addHandler(logging.NullHandler())
 
+F = TypeVar('F', bound=Callable[..., Any])
 
-def log(method):
+
+def log(method: F) -> F:
     logger = logging.getLogger(method.__module__)
 
     @functools.wraps(method)
-    def wrapper(*args, **kwargs):
+    def wrapper(*args, **kwargs) -> Any:
         logger.debug(f'Entering: {method.__name__}')
 
         result = method(*args, **kwargs)
diff --git a/yandex_music/client_async.py b/yandex_music/client_async.py
index f3992e5..a3daa9c 100644
--- a/yandex_music/client_async.py
+++ b/yandex_music/client_async.py
@@ -5,7 +5,7 @@
 import functools
 import logging
 from datetime import datetime
-from typing import Dict, List, Optional, Union
+from typing import Dict, List, Optional, Union, TypeVar, Callable, Any
 
 from yandex_music import (
     Album,
@@ -59,12 +59,14 @@ de_list = {
 
 logging.getLogger(__name__).addHandler(logging.NullHandler())
 
+F = TypeVar('F', bound=Callable[..., Any])
 
-def log(method):
+
+def log(method: F) -> F:
     logger = logging.getLogger(method.__module__)
 
     @functools.wraps(method)
-    async def wrapper(*args, **kwargs):
+    async def wrapper(*args, **kwargs) -> Any:
         logger.debug(f'Entering: {method.__name__}')
 
         result = await method(*args, **kwargs)