docs: def add(self, task_cls):
  		""" Add task to this storage. Depends on :attr:`.WTaskRegistryStorage.__multiple_tasks_per_tag__`
  		tasks with the same __registry_tag__ can be treated as error.
  
  		:param task_cls: task to add
  		:return: None
  		"""
  
  		registry_tag = task_cls.__registry_tag__
  		if registry_tag not in self.__registry.keys():
  			self.__registry[registry_tag] = [task_cls]
  		elif self.__multiple_tasks_per_tag__ is True:
  			self.__registry[registry_tag].append(task_cls)
  		else:
  			raise RuntimeError('Multiple tasks with same tag appended')