NSDictionary *course_dict = @{
                              @"CS 1" : @[],
                              @"CS 31" : @[],
                              @"CS 32" : @[@"CS 31"],
                              @"CS 33" : @[@"CS 32"],
                              @"CS 35L" : @[@"CS 31"],
                              @"CS M51A" : @[],
                              @"CS 111" : @[@"CS 32", @"CS 33", @"CS 35L"],
                              @"CS M117" : @[],
                              @"CS M151B" : @[@"CS 33", @"CS M51A"],
                              @"CS 130" : @[@"CS 111"],
                              @"CS 131" : @[@"CS 33", @"CS 35L"],
                              @"CS 118" : @[@"CS 111"],
                              @"CS 152A" : @[@"CS M51A"],
                              @"CS 152B" : @[@"CS 151B"],
                              @"CS 180" : @[@"CS 31", @"Math 61"],
                              @"CS 181" : @[@"180"],
                              @"Math 31A" : @[],
                              @"Math 31B" : @[@"Math 31A"],
                              @"Math 32A" : @[@"Math 31A"],
                              @"Math 32B" : @[@"Math 31B", @"Math 32A"],
                              @"Math 33A" : @[@"Math 32A"],
                              @"Math 33B" : @[@"Math 31B"],
                              @"Math 61" : @[@"Math 31A", @"Math 31B"],
                              @"Phy 1A" : @[@"Math 31A", @"Math 31B"],
                              @"Phy 1B" : @[@"Phy 1A", @"Math 32A", @"Math 31B"],
                              @"Phy 1C" : @[@"Phy 1A", @"Phy 1B", @"Math 32A", @"Math 32B"],
                              @"Phy 4AL" : @[@"Phy 1A"],
                              @"Phy 4BL" : @[@"Phy 1A", @"Phy 1B"],
                              };

    // create registrar
    NSMutableArray *courses;

    // for each course
    for (id key in course_dict) {
        Course *course = [[Course alloc] init];
        course.name = key;
        // for each prereq
        for (id prereq in [course_dict objectForKey:key]) {
            // add it to the list of prereqs
            Course *p = [[Course alloc] init];
            p.name = prereq;
            [course.prereqs addObject:p];
        }
    }