diff --git a/telebot/__init__.py b/telebot/__init__.py
index ca93487..5f299a6 100644
--- a/telebot/__init__.py
+++ b/telebot/__init__.py
@@ -252,7 +252,7 @@ class TeleBot:
         """
 
         self.current_states = StateFile(filename=filename)
-        self.current_states._create_dir()
+        self.current_states.create_dir()
 
     def enable_save_reply_handlers(self, delay=120, filename="./.handler-saves/reply.save"):
         """
@@ -1221,11 +1221,13 @@ class TeleBot:
                 reply_to_message_id = reply_to_message_id, reply_markup = reply_markup, parse_mode = parse_mode,
                 disable_notification = disable_notification, timeout = timeout, caption = caption, thumb = thumb,
                 caption_entities = caption_entities, allow_sending_without_reply = allow_sending_without_reply,
-                disable_content_type_detection = disable_content_type_detection, visible_file_name = visible_file_name, protect_content = protect_content))
+                disable_content_type_detection = disable_content_type_detection, visible_file_name = visible_file_name,
+                protect_content = protect_content))
 
     # TODO: Rewrite this method like in API.
     def send_sticker(
-            self, chat_id: Union[int, str], sticker: Union[Any, str], 
+            self, chat_id: Union[int, str],
+            sticker: Union[Any, str],
             reply_to_message_id: Optional[int]=None, 
             reply_markup: Optional[REPLY_MARKUP_TYPES]=None,
             disable_notification: Optional[bool]=None, 
@@ -1236,6 +1238,7 @@ class TeleBot:
         """
         Use this method to send .webp stickers.
         :param chat_id:
+        :param sticker:
         :param data:
         :param reply_to_message_id:
         :param reply_markup:
@@ -1254,7 +1257,8 @@ class TeleBot:
                 self.token, chat_id, sticker, 'sticker',
                 reply_to_message_id=reply_to_message_id, reply_markup=reply_markup,
                 disable_notification=disable_notification, timeout=timeout, 
-                allow_sending_without_reply=allow_sending_without_reply, protect_content=protect_content))
+                allow_sending_without_reply=allow_sending_without_reply,
+                protect_content=protect_content))
 
     def send_video(
             self, chat_id: Union[int, str], video: Union[Any, str], 
@@ -1330,6 +1334,7 @@ class TeleBot:
         :param thumb: InputFile or String : Thumbnail of the file sent
         :param caption: String : Animation caption (may also be used when resending animation by file_id).
         :param parse_mode:
+        :param protect_content:
         :param reply_to_message_id:
         :param reply_markup:
         :param disable_notification:
@@ -2559,7 +2564,7 @@ class TeleBot:
         :param chat_id:
         """
         for key, value in kwargs.items():
-            self.current_states._add_data(chat_id, key, value)
+            self.current_states.add_data(chat_id, key, value)
 
     def register_next_step_handler_by_chat_id(
             self, chat_id: Union[int, str], callback: Callable, *args, **kwargs) -> None:
diff --git a/telebot/apihelper.py b/telebot/apihelper.py
index 3f9562d..870c609 100644
--- a/telebot/apihelper.py
+++ b/telebot/apihelper.py
@@ -144,6 +144,7 @@ def _make_request(token, method_name, method='get', params=None, files=None):
             method, request_url, params=params, files=files,
             timeout=(connect_timeout, read_timeout), proxies=proxy)
     elif CUSTOM_REQUEST_SENDER:
+        # noinspection PyCallingNonCallable
         result = CUSTOM_REQUEST_SENDER(
             method, request_url, params=params, files=files,
             timeout=(connect_timeout, read_timeout), proxies=proxy)
@@ -246,6 +247,7 @@ def send_message(
     :param timeout:
     :param entities:
     :param allow_sending_without_reply:
+    :param protect_content:
     :return:
     """
     method_url = r'sendMessage'
@@ -861,7 +863,8 @@ def send_audio(token, chat_id, audio, caption=None, duration=None, performer=Non
 
 def send_data(token, chat_id, data, data_type, reply_to_message_id=None, reply_markup=None, parse_mode=None,
               disable_notification=None, timeout=None, caption=None, thumb=None, caption_entities=None,
-              allow_sending_without_reply=None, disable_content_type_detection=None, visible_file_name=None):
+              allow_sending_without_reply=None, disable_content_type_detection=None, visible_file_name=None,
+              protect_content = None):
     method_url = get_method_by_type(data_type)
     payload = {'chat_id': chat_id}
     files = None
@@ -896,6 +899,8 @@ def send_data(token, chat_id, data, data_type, reply_to_message_id=None, reply_m
         payload['caption_entities'] = json.dumps(types.MessageEntity.to_list_of_dicts(caption_entities))
     if allow_sending_without_reply is not None:
         payload['allow_sending_without_reply'] = allow_sending_without_reply
+    if protect_content is not None:
+        payload['protect_content'] = protect_content
     if method_url == 'sendDocument' and disable_content_type_detection is not None:
         payload['disable_content_type_detection'] = disable_content_type_detection
     return _make_request(token, method_url, params=payload, files=files, method='post')
@@ -1382,6 +1387,7 @@ def send_invoice(
     :param max_tip_amount: The maximum accepted amount for tips in the smallest units of the currency
     :param suggested_tip_amounts: A JSON-serialized array of suggested amounts of tips in the smallest units of the currency.
         At most 4 suggested tip amounts can be specified. The suggested tip amounts must be positive, passed in a strictly increased order and must not exceed max_tip_amount.
+    :param protect_content:
     :return:
     """
     method_url = r'sendInvoice'
diff --git a/telebot/handler_backends.py b/telebot/handler_backends.py
index 45b903b..6f12c35 100644
--- a/telebot/handler_backends.py
+++ b/telebot/handler_backends.py
@@ -168,7 +168,7 @@ class StateMemory:
         """Delete a state"""
         self._states.pop(chat_id)
 
-    def _get_data(self, chat_id):
+    def get_data(self, chat_id):
         return self._states[chat_id]['data']
 
     def set(self, chat_id, new_state):
@@ -179,7 +179,7 @@ class StateMemory:
         """
         self.add_state(chat_id,new_state)
 
-    def _add_data(self, chat_id, key, value):
+    def add_data(self, chat_id, key, value):
         result = self._states[chat_id]['data'][key] = value
         return result
 
@@ -217,28 +217,27 @@ class StateFile:
         :param chat_id:
         :param state: new state
         """
-        states_data = self._read_data()
+        states_data = self.read_data()
         if chat_id in states_data:
             states_data[chat_id]['state'] = state
-            return self._save_data(states_data)
+            return self.save_data(states_data)
         else:
-            new_data = states_data[chat_id] = {'state': state,'data': {}}
-            return self._save_data(states_data)
-
+            states_data[chat_id] = {'state': state,'data': {}}
+            return self.save_data(states_data)
 
     def current_state(self, chat_id):
         """Current state."""
-        states_data = self._read_data()
+        states_data = self.read_data()
         if chat_id in states_data: return states_data[chat_id]['state']
         else: return False
 
     def delete_state(self, chat_id):
         """Delete a state"""
-        states_data = self._read_data()
+        states_data = self.read_data()
         states_data.pop(chat_id)
-        self._save_data(states_data)
+        self.save_data(states_data)
 
-    def _read_data(self):
+    def read_data(self):
         """
         Read the data from file.
         """
@@ -247,7 +246,7 @@ class StateFile:
         file.close()
         return states_data
 
-    def _create_dir(self):
+    def create_dir(self):
         """
         Create directory .save-handlers.
         """
@@ -257,7 +256,7 @@ class StateFile:
             with open(self.file_path,'wb') as file:
                 pickle.dump({}, file)
         
-    def _save_data(self, new_data):
+    def save_data(self, new_data):
         """
         Save data after editing.
         :param new_data:
@@ -266,23 +265,21 @@ class StateFile:
             pickle.dump(new_data, state_file, protocol=pickle.HIGHEST_PROTOCOL)
         return True
 
-    def _get_data(self, chat_id):
-        return self._read_data()[chat_id]['data']
+    def get_data(self, chat_id):
+        return self.read_data()[chat_id]['data']
 
     def set(self, chat_id, new_state):
         """
         Set a new state for a user.
         :param chat_id:
         :param new_state: new_state of a user
-        
         """
         self.add_state(chat_id,new_state)
 
     def _add_data(self, chat_id, key, value):
-        states_data = self._read_data()
+        states_data = self.read_data()
         result = states_data[chat_id]['data'][key] = value
-        self._save_data(result)
-
+        self.save_data(result)
         return result
 
     def finish(self, chat_id):
@@ -313,7 +310,7 @@ class StateContext:
     def __init__(self , obj: StateMemory, chat_id) -> None:
         self.obj = obj
         self.chat_id = chat_id
-        self.data = obj._get_data(chat_id)
+        self.data = obj.get_data(chat_id)
 
     def __enter__(self):
         return self.data
@@ -321,6 +318,7 @@ class StateContext:
     def __exit__(self, exc_type, exc_val, exc_tb):
         return
 
+
 class StateFileContext:
     """
     Class for data.
@@ -328,15 +326,14 @@ class StateFileContext:
     def __init__(self , obj: StateFile, chat_id) -> None:
         self.obj = obj
         self.chat_id = chat_id
-        self.data = self.obj._get_data(self.chat_id)
+        self.data = self.obj.get_data(self.chat_id)
 
     def __enter__(self):
         return self.data
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        old_data = self.obj._read_data()
+        old_data = self.obj.read_data()
         for i in self.data:
             old_data[self.chat_id]['data'][i] = self.data.get(i)
-        self.obj._save_data(old_data)
-
+        self.obj.save_data(old_data)
         return
diff --git a/telebot/util.py b/telebot/util.py
index 1ab6201..414fa56 100644
--- a/telebot/util.py
+++ b/telebot/util.py
@@ -449,7 +449,7 @@ def deprecated(warn: bool=False, alternative: Optional[Callable]=None):
                 logger.info(f"`{function.__name__}` is deprecated." 
                     + (f" Use `{alternative.__name__}` instead" if alternative else ""))
             else:
-                logger.warn(f"`{function.__name__}` is deprecated." 
+                logger.warning(f"`{function.__name__}` is deprecated."
                     + (f" Use `{alternative.__name__}` instead" if alternative else ""))
             return function(*args, **kwargs)
         return wrapper
@@ -484,6 +484,7 @@ def antiflood(function, *args, **kwargs):
     """
     from telebot.apihelper import ApiTelegramException
     from time import sleep
+    msg = None
     try:
         msg = function(*args, **kwargs)
     except ApiTelegramException as ex:
@@ -491,4 +492,4 @@ def antiflood(function, *args, **kwargs):
             sleep(ex.result_json['parameters']['retry_after'])
             msg = function(*args, **kwargs)
     finally:
-        return msg
\ No newline at end of file
+        return msg
diff --git a/telebot/version.py b/telebot/version.py
index 42af8f6..531afbd 100644
--- a/telebot/version.py
+++ b/telebot/version.py
@@ -1,3 +1,3 @@
 # Versions should comply with PEP440.
 # This line is parsed in setup.py:
-__version__ = '4.3.0'
+__version__ = '4.3.1'