code: def del_fields(self, *names):
          
          cls = type(self)
          self.__class__ = cls
          for n in names:
              # don't raise error if a field is absent
              if isinstance(getattr(cls, n, None), DataField):
                  if n in self._field_values:
                      del self._field_values[n]
                  delattr(cls, n)
docs: Delete data fields from this struct instance