code: def get_filter_options(cls):
          
          attr = '_filter_options_%s' % id(cls)
  
          options = getattr(cls, attr, {})
          if options:
              return options
  
          for key in dir(cls):
              val = getattr(cls, key)
              if isinstance(val, FilterOpt):
                  options[key] = val
  
          setattr(cls, attr, options)
          return options
docs: List all filter options defined on class (and superclasses)