docs: def tasks(self, task_cls=None):
  		""" :meth:`.WTaskRegistryBase.tasks` implementation
  		"""
  		result = []
  		for tasks in self.__registry.values():
  			result.extend(tasks)
  
  		if task_cls is not None:
  			result = filter(lambda x: issubclass(x, task_cls), result)
  		return tuple(result)