so finally

Thanks PC

telethon/client/chats.py

@@ -789,7 +789,8 @@ class ChatMethods:
             try:
                 action = _ChatAction._str_mapping[action.lower()]
             except KeyError:
-                raise ValueError('No such action "{}"'.format(action)) from None
+                raise ValueError(
+                    'No such action "{}"'.format(action)) from None
         elif not isinstance(action, types.TLObject) or action.SUBCLASS_OF_ID != 0x20b2cc21:
             # 0x20b2cc21 = crc32(b'SendMessageAction')
             if isinstance(action, type):
@@ -954,7 +955,8 @@ class ChatMethods:
                 entity, user, is_admin=is_admin))
 
         else:
-            raise ValueError('You can only edit permissions in groups and channels')
+            raise ValueError(
+                'You can only edit permissions in groups and channels')
 
     async def edit_permissions(
             self: 'TelegramClient',
@@ -1313,27 +1315,85 @@ class ChatMethods:
         finally:
             await self._return_exported_sender(sender)
 
-    async def change_groupcall(method:str,
-                               chat,
-                               title:str=None):
-        if not method:
-            return
-        if method == "create":
-            InputPeer = utils.get_input_peer(chat)
-            return await self(
-                functions.phone.CreateGroupCallRequest(peer=InputPeer)
-                )
-        try:
-            Call = (await self(functions.messages.GetFullChatRequest(chat))).full_chat.call
-        except errors.rpcerrorlist.ChatIdInvalidError:
-            Call = (await self(functions.channels.GetFullChannelRequest(chat))).full_chat.call
-        if method == "edit_title":
-            return await self(functions.phone.EditGroupCallTitleRequest(Call, title=title))
-        elif method == "discard":
-            return await self(functions.phone.DiscardGroupCallRequest(call))
-        else:
-            self._log[__name__].info("Invalid Method Invoked while using change_groupcall")            
+    async def modify_groupcall(
+        self: 'TelegramClient',
+        method: str,
+        entity: 'hints.EntityLike',
+        schedule: 'hints.DateLike' = None,
+        title: str = None
+    ):    
+        """
+        Stuff to do with Group Calls, Possible for Administrator and
+        Creator.
 
+        Arguments
+            method (`str`):
+                Any of `create`, `discard`, `start_schedule` and 
+                `edit_title` will work. Check Examples to know more Clearly.
+
+            entity (`int` | `str`):
+                Username/ID of Channel, where to Modify Group Call.
+
+            schedule (`hints.Datelike`, optional):
+                Used to Schedule the GroupCall.
+            
+            title (str, optional):
+                Edits the Group call Title. It should be used with
+                `edit_title` as method parameter.
+
+        Returns
+            The resulting :tl:`Updates` object.
         
+        Raises
+            ChatAdminRequiredError - You Should be Admin, in order to
+            Modify Group Call.
+        
+        Example
+        .. code-block:: python
 
-    # endregion
+                # Starting a Group Call
+                await client.modify_groupcall("create", -100123456789)
+                
+                # Scheduling a Group Call, within 5-Minutes
+                from datetime import timedelta
+                schedule_for = timedelta(minutes=5)
+                await client.modify_groupcall(
+                    "create",
+                    schedule=schedule_for
+                )
+                
+                # Editing a Group Call Title
+                new_title = "Having Fun with Telethon"
+                await client.modify_groupcall(
+                    "edit_title",
+                    title=new_title
+                )
+
+                # Stopping/Closing a Group Call
+                await client.modify_groupcall("discard", -100123456789)
+        """
+        if not method:
+            return self._log[__name__].info("Method Cant be None.")
+        
+        if method == "create" :
+            return await self(
+                functions.phone.CreateGroupCallRequest(
+                    peer=entity,
+                    schedule=schedule)
+            ).updates[0]
+        try:
+            Call = await self(functions.messages.GetFullChatRequest(entity))
+        except errors.rpcerrorlist.ChatIdInvalidError:
+            Call = await self(functions. channels.GetFullChannelRequest(entity))
+        if method == "edit_title":
+            return (await self(functions.phone.EditGroupCallTitleRequest(
+                Call, title=title if title else ""))).updates
+        elif method == "discard":
+            return (await self(functions.phone.DiscardGroupCallRequest(Call))).updates
+        elif method == "start_schedule":
+            return (await self(functions.phone.StartScheduledGroupCallRequest(Call))).updates
+        else:
+            self._log[__name__].info(
+                "Invalid Method Used while using Modifying GroupCall")
+
+    # endregion

telethon_generator/data/errors.csv

@@ -216,6 +216,7 @@ PACK_SHORT_NAME_INVALID,400,"Invalid sticker pack name. It must begin with a let
 PACK_SHORT_NAME_OCCUPIED,400,A stickerpack with this name already exists
 PARTICIPANTS_TOO_FEW,400,Not enough participants
 PARTICIPANT_CALL_FAILED,500,Failure while making call
+PARTICIPANT_JOIN_MISSING,403,
 PARTICIPANT_VERSION_OUTDATED,400,The other participant does not use an up to date telegram client with support for calls
 PASSWORD_EMPTY,400,The provided password is empty
 PASSWORD_HASH_INVALID,400,The password (and thus its hash value) you entered is invalid
@@ -288,6 +289,7 @@ RPC_CALL_FAIL,500,"Telegram is having internal issues, please try again later."
 RPC_MCGET_FAIL,500,"Telegram is having internal issues, please try again later."
 RSA_DECRYPT_FAILED,400,Internal RSA decryption failed
 SCHEDULE_BOT_NOT_ALLOWED,400,Bots are not allowed to schedule messages
+SCHEDULE_DATE_INVALID,400,
 SCHEDULE_DATE_TOO_LATE,400,The date you tried to schedule is too far in the future (last known limit of 1 year and a few hours)
 SCHEDULE_STATUS_PRIVATE,400,You cannot schedule a message until the person comes online if their privacy does not show this information
 SCHEDULE_TOO_MUCH,400,You cannot schedule more messages in this chat (last known limit of 100 per chat)

telethon_generator/data/methods.csv

@@ -308,10 +308,12 @@ payments.sendPaymentForm,user,MESSAGE_ID_INVALID
 payments.validateRequestedInfo,user,MESSAGE_ID_INVALID
 phone.acceptCall,user,CALL_ALREADY_ACCEPTED CALL_ALREADY_DECLINED CALL_OCCUPY_FAILED CALL_PEER_INVALID CALL_PROTOCOL_FLAGS_INVALID
 phone.confirmCall,user,CALL_ALREADY_DECLINED CALL_PEER_INVALID
+phone.createGroupCall,user,SCHEDULE_DATE_INVALID 
 phone.discardCall,user,CALL_ALREADY_ACCEPTED CALL_PEER_INVALID
 phone.getCallConfig,user,
 phone.inviteToGroupCall,user,GROUPCALL_FORBIDDEN
 phone.joinGroupCall,user,GROUPCALL_SSRC_DUPLICATE_MUCH
+phone.joinGroupCallPresentation,403, PARTICIPANT_JOIN_MISSING
 phone.receivedCall,user,CALL_ALREADY_DECLINED CALL_PEER_INVALID
 phone.requestCall,user,CALL_PROTOCOL_FLAGS_INVALID PARTICIPANT_CALL_FAILED PARTICIPANT_VERSION_OUTDATED USER_ID_INVALID USER_IS_BLOCKED USER_PRIVACY_RESTRICTED
 phone.saveCallDebug,user,CALL_PEER_INVALID DATA_JSON_INVALID