code: def add_recipe_folder(self, recipe_folder, whitelist=None):
          if whitelist is not None:
              whitelist = set(whitelist)
          if recipe_folder == '':
              recipe_folder = '.'
          for yaml_file in [x for x in os.listdir(recipe_folder) if x.endswith('.yaml')]:
              if whitelist is not None and yaml_file not in whitelist:
                  continue
              recipe = RecipeObject.FromFile(os.path.join(recipe_folder, yaml_file), self._recipe_actions, self._recipe_resources)
              self._recipes[recipe.name] = recipe
          for ship_file in [x for x in os.listdir(recipe_folder) if x.endswith('.ship')]:
              if whitelist is not None and ship_file not in whitelist:
                  continue
              recipe = RecipeObject.FromArchive(os.path.join(recipe_folder, ship_file), self._recipe_actions, self._recipe_resources)
              self._recipes[recipe.name] = recipe