code: def _unpack_oxm_field(self):
          
          field_int = self.oxm_field_and_mask >> 1
          # We know that the class below requires a subset of the ofb enum
          if self.oxm_class == OxmClass.OFPXMC_OPENFLOW_BASIC:
              return OxmOfbMatchField(field_int)
          return field_int
docs: Unpack oxm_field from oxm_field_and_mask.
  
          Returns:
              :class:`OxmOfbMatchField`, int: oxm_field from oxm_field_and_mask.
  
          Raises:
              ValueError: If oxm_class is OFPXMC_OPENFLOW_BASIC but
                  :class:`OxmOfbMatchField` has no such integer value.