docs: def apply_filters(query, args):
      """
      Apply all QueryFilters, validating the querystring in the process.
      """
      pre_joins = []
      for querystring_key, filter_value in args.items(multi=True):
          if querystring_key in filter_registry:
              cls_inst = filter_registry[querystring_key]
              query = cls_inst.apply_filter(query, args, pre_joins)
          elif querystring_key in PaginationKeys._value_list:
              pass
          else:
              raise InvalidQueryString(querystring_key, filter_value)
      return query