code: def get_size(self, value=None):
          
          if isinstance(value, ActionHeader):
              return value.get_size()
          elif value is None:
              current_size = super().get_size()
              return ceil(current_size / 8) * 8
          raise ValueError(f'Invalid value "{value}" for Action*.get_size()')
docs: Return the action length including the padding (multiple of 8).