docs: def _extract_lookup(self, key):
          """Extract lookup method based on key name format"""
          parts = key.split('__')
          # 'exact' is the default lookup if there was no explicit comparison op in `key`
          #   Assume there is only one `__` in the key.
          #   FIXME Change for child attribute query support
          op = 'exact' if len(parts) == 1 else parts[1]
  
          # Construct and assign the lookup class as a filter criteria
          return parts[0], self.get_lookup(op)