diff --git a/telebot/__init__.py b/telebot/__init__.py
index b8b0c6e..64cf2c7 100644
--- a/telebot/__init__.py
+++ b/telebot/__init__.py
@@ -357,7 +357,7 @@ class TeleBot:
         """
         return apihelper.delete_webhook(self.token, drop_pending_updates, timeout)
 
-    def get_webhook_info(self, timeout=None):
+    def get_webhook_info(self, timeout: Optional[int]=None):
         """
         Use this method to get current webhook status. Requires no parameters.
         If the bot is using getUpdates, will return an object with the url field empty.
@@ -2381,7 +2381,7 @@ class TeleBot:
         chat_id = message.chat.id
         self.register_next_step_handler_by_chat_id(chat_id, callback, *args, **kwargs)
 
-    def set_state(self, chat_id, state):
+    def set_state(self, chat_id: int, state: Union[int, str]):
         """
         Sets a new state of a user.
         :param chat_id:
@@ -2389,7 +2389,7 @@ class TeleBot:
         """
         self.current_states.add_state(chat_id, state)
 
-    def delete_state(self, chat_id):
+    def delete_state(self, chat_id: int):
         """
         Delete the current state of a user.
         :param chat_id:
@@ -2397,10 +2397,10 @@ class TeleBot:
         """
         self.current_states.delete_state(chat_id)
 
-    def retrieve_data(self, chat_id):
+    def retrieve_data(self, chat_id: int):
         return self.current_states.retrieve_data(chat_id)
 
-    def get_state(self, chat_id):
+    def get_state(self, chat_id: int):
         """
         Get current state of a user.
         :param chat_id:
@@ -2408,7 +2408,7 @@ class TeleBot:
         """
         return self.current_states.current_state(chat_id)
 
-    def add_data(self, chat_id, **kwargs):
+    def add_data(self, chat_id: int, **kwargs):
         """
         Add data to states.
         :param chat_id: