Find the first names of professors who are teaching more than one class.
SELECT T2.emp_fname FROM CLASS AS T1 JOIN employee AS T2 ON T1.prof_num  =  T2.emp_num GROUP BY T1.prof_num HAVING count(*)  >  1
SELECT T2.emp_fname FROM CLASS AS T1 JOIN employee AS T2 ON T1.prof_num  =  T2.emp_num GROUP BY T1.prof_num HAVING count(*)  >  1
[{'EMP_FNAME': 'Arnelle'}, {'EMP_FNAME': 'Gerald'}, {'EMP_FNAME': 'Peter'}, {'EMP_FNAME': 'Carlos'}, {'EMP_FNAME': 'Ismael'}]