code: def _g(self, word, key_expand_round):
          
          import numbers
          self._build_memories_if_not_exists()
          a = libutils.partition_wire(word, 8)
          sub = [self.sbox[a[index]] for index in (3, 0, 1, 2)]
          if isinstance(key_expand_round, numbers.Number):
              rcon_data = self._rcon_data[key_expand_round + 1]  # int value
          else:
              rcon_data = self.rcon[key_expand_round + 1]
          sub[3] = sub[3] ^ rcon_data
          return pyrtl.concat_list(sub)
docs: One-byte left circular rotation, substitution of each byte