def make_attribute(self, items=None):
								"""Called on the attr_cl. This function will return the list for the attribute.
								 As a default, this is [], but a list can also be passed in"""
								if items==None:
									items=[]		
								if self.__vals__[key]==None:
									self.__vals__[key]=items
								else:
									raise RuntimeError("This attribute has been already initialised")	
								return self.__vals__[key]
Called on the attr_cl. This function will return the list for the attribute.
								 As a default, this is [], but a list can also be passed in
recipes/Python/577092_Virtual_collections/recipe-577092.py