anchor.diff:      + Attributes (Professor, required)
           + evaluations (array, required, fixed-type)
               + (Evaluation, required)
  -                + user_vote: true (boolean, required)
  +                + user_vote: u, d (enum[string], required)
  +                + user_flagged: false (boolean, required) 
                   + quarter_id: 3900 (number, required)
                   + course (Course, required)
                   + author (required)
  
positive.code:     + Attributes (Course, required)
          + evaluations (array, required, fixed-type)
              + (Evaluation, required)
                  + user_vote: true (boolean, required)
                  + quarter_id: 3900 (number, required)
                  + professor (Professor, required)
                  + author (required)
  
negative.code: 
  ## Course (object)
  + id: 1 (number, required)
  + number: 42 (string, required)
  + title: What is Life (string, required)
  + department_id: 3 (number, required)
  
  