SQLite syntax error says `near "constraint": syntax error`

Question

I am trying to execute sql syntax like this

alter table PRESENSI_KELASS
    add constraint FK_RELATION_556 foreign key  (ID_BOOKING_KELAS)
       references BOOKING_KELASS (ID_BOOKING_KELAS)
;

However, I instead got an error message like this

Execution finished with errors.
Result: near "constraint": syntax error
At line 1:
alter table PRESENSI_KELASS
    add constraint

I have activated the foreign_key pragmas

What's the correct syntax?