Consider the following BNF grammar that describes some of the "technical elective" courses allowed by the CS degree plan.  ->   ->  |    -> CS4390 | CS4371 | CS4373 | CS4330 | CS4317 | CS4339 | CS4342 You need to take at least five technical elective courses. However, no more than two courses of CS4390 (Special Topics), CS4371 (Independent Studies) and CS4373 (Internship) in any combination can count for technical electives. CS4390 CS4330 CS4317 CS4339 CS4342 -- ok: one special course CS4390 CS4390 CS4317 CS4339 CS4342 -- ok: two CS4390 CS4371 CS4317 CS4339 CS4342 -- ok: two CS4390 CS4390 CS4390 CS4330 CS4317 CS4339 -- ok: why? CS4390 CS4330 CS4317 -- not okay: < five CS4390 CS4390 CS4373 CS4330 CS4342 -- not okay: three Extend the given BNF grammar to an attribute grammar to specify the above rules.