LET x = 0

GOSUB double
GOSUB add_one
GOSUB double
GOSUB double
GOSUB add_one

IF x == 5 THEN
    PRINT "success"
ELSE
    PRINT "fail"
END IF

END
PRINT "unreachable (after END)\n"

double:
    x = x * 2
    RETURN
    PRINT "unreachable (after RETURN in double)\n"

add_one:
    x = x + 1
    RETURN
    PRINT "unreachable (after RETURN in add_one)\n"