code: def active_aliases(self):
          
          whitelisted_aliases = self.app.config.get('SEARCH_MAPPINGS')
          if whitelisted_aliases is None:
              return self.aliases
          else:
              return {k: v for k, v in self.aliases.items()
                      if k in whitelisted_aliases}
docs: Get a filtered list of aliases based on configuration.
  
          Returns aliases and their mappings that are defined in the
          `SEARCH_MAPPINGS` config variable. If the `SEARCH_MAPPINGS` is set to
          `None` (the default), all aliases are included.