code: def pack(self):
          
          # # 22-bytes Yubikey secrets block
          # typedef struct {
          #   uint8_t key[KEY_SIZE];              // AES key
          #   uint8_t uid[UID_SIZE];              // Unique (secret) ID
          # } YUBIKEY_SECRETS;
          return self.key + self.uid.ljust(pyhsm.defines.UID_SIZE, chr(0))
docs: Return key and uid packed for sending in a command to the YubiHSM.