NOTA  testing embedded loops feature of class SEO_simulator. 14 ops
SIGX	AT	0	IF	2F
LOOP    20  REPS:   2
    SIGX	AT	1	IF	2F
    LOOP	10	REPS:	4
        SIGX	AT	2	IF	3T
    NEXT    10
    SIGX	AT	1	IF	2F
NEXT    20
SIGX	AT	0	IF	2F
SIGX    AT  1