code: def filter_commands(text, chat_id, correct_ident):
      
      is_group = (chat_id < 0)  # always negative for groups
      split_cmd = text.split()[:2]
      command = split_cmd[0].strip().lower()
  
      # make sure command is known
      if command not in ('/activate', '/deactivate', '/help'):
          return
      # dont check bot_ident if not in group
      if not is_group:
          return command
      # check bot_ident
      if len(split_cmd) < 2:
          return 'no_ident'
      if split_cmd[1].strip() != correct_ident:
          return 'wrong_ident'
  
      return command
docs: Check if text is valid command to bot.
      Return string(either some command or error name) or None.
      Telegram group may have many participants including bots,
      so we need to check bot identifier to make sure command is
      given to our bot.