code: def find_or_create_by_name(self, item_name, items_list, item_type):
          
          item = self.find_by_name(item_name, items_list)
          if not item:
              item = self.data_lists[item_type][2](item_name, None)
          return item
docs: See if item with item_name exists in item_list.
          If not, create that item.
          Either way, return an item of type item_type.