code: private ClassRecord getClassRecord(Integer classId) {
  		if (!this.classRecords.containsKey(classId)) {
  			ClassRecord classRecord = new ClassRecord();
  			this.classRecords.put(classId, classRecord);
  			return classRecord;
  		} else {
  			return this.classRecords.get(classId);
  		}
  	}
docs: Returns record where statistics about a class should be stored.
  
  @param classId
  the numeric id of the class to initialize
  @return the class record