anchor.diff:      + professor_id: 1 (number, optional)
       + course_id: 1 (number, optional)
       + quarter_id: 1 (number, optional)
  -    + embed (array, optional)
  -        + (enum)
  -            + professor
  -            + course
  +    + embed (array[string], optional) - Specify one or more of the following: professor, course.
   
   + Response 200 (application/json)
       + Attributes (array, required, fixed-type)
  
positive.code:     + course_id: 1 (number, optional)
      + quarter_id: 1 (number, optional)
      + embed (array, optional)
          + (enum)
              + professor
              + course
  
  
negative.code: 
  + Response 200 (application/json)
      + Attributes (array[Professor], required, fixed-type)
      
  
  ### List Top Professors [GET /professors/top{?count,department_id}]
  
  + Parameters
      + count (number, optional)
          + Default: 5
      + department_id (array[number], optional)
  
  + Response 200 (application/json)
      + Attributes (array, required, fixed-type)
          + (object, required)
              + professor (Professor, required)
              + avg_score: 3.0 (number, required)
              
  + Response 404 (application/json)
      + Attributes
          + message: `department with id <id> not found` (string, required)
  
  
  ### Get Professor Details [GET /professors/{id}{?embed}]
  
  