code: def _getextra(self):
          '''
          Get the extra data of this struct.
          '''
          current = self
          while hasattr(current, '_sub'):
              current = current._sub
          return getattr(current, '_extra', Nonef _getextra(self):
          '''
          Get the extra data of this struct.
          '''
          current = self
          while hasattr(current, '_sub'):
              current = current._sub
          return getattr(current, '_extra', None)
docs: Get the extra data of this struct.