code: def add_cog(self, cog):
          
  
          if not isinstance(cog, Cog):
              raise TypeError('cogs must derive from Cog')
  
          cog = cog._inject(self)
          self.__cogs[cog.__cog_name__] = cog
docs: Adds a "cog" to the bot.
  
          A cog is a class that has its own event listeners and commands.
  
          Parameters
          -----------
          cog: :class:`.Cog`
              The cog to register to the bot.
  
          Raises
          -------
          TypeError
              The cog does not inherit from :class:`.Cog`.
          CommandError
              An error happened during loading.