Find the title of courses that have two prerequisites?
SELECT T1.title FROM course AS T1 JOIN prereq AS T2 ON T1.course_id  =  T2.course_id GROUP BY T2.course_id HAVING count(*)  =  2
SELECT T1.title FROM course AS T1 JOIN prereq AS T2 ON T1.course_id  =  T2.course_id GROUP BY T2.course_id HAVING count(*)  =  2
[{'title': 'Rock and Roll'}, {'title': 'Ponzi Schemes'}, {'title': 'Graph Theory'}, {'title': 'Operating Systems'}, {'title': 'Game Programming'}, {'title': 'Embedded Systems'}, {'title': 'Immunology'}, {'title': 'Differential Geometry'}, {'title': 'International Practicum'}, {'title': 'Electron Microscopy'}, {'title': 'Groups and Rings'}, {'title': 'Elastic Structures'}, {'title': 'International Practicum'}, {'title': 'Game Programming'}, {'title': 'World History'}]