code: def get_duration(self):
          
          # Implemented from template for osid.assessment.AssessmentOffered.get_duration_template
          if not bool(self._my_map['duration']):
              raise errors.IllegalState()
          return Duration(**self._my_map['duration'])
docs: Gets the duration for this assessment.
  
          return: (osid.calendaring.Duration) - the duration
          raise:  IllegalState - ``has_duration()`` is ``false``
          *compliance: mandatory -- This method must be implemented.*