docs: def has_started(self):
          """Tests if this assessment has begun.
  
          return: (boolean) - ``true`` if the assessment has begun,
                  ``false`` otherwise
          *compliance: mandatory -- This method must be implemented.*
  
          """
          assessment_offered = self.get_assessment_offered()
          if assessment_offered.has_start_time():
              return DateTime.utcnow() >= assessment_offered.get_start_time()
          else:
              return True