docs: def multi_grade(self, grade_array, gradebook_id=''):
          """Set multiple grades for students.
  
          Set multiple student grades for a gradebook.  The grades are passed
          as a list of dictionaries.
  
          Each grade dictionary in ``grade_array`` must contain a
          ``studentId`` and a ``assignmentId``.
          Options for grade mode are: OVERALL_GRADE = ``1``,
          REGULAR_GRADE = ``2``
          To set 'excused' as the grade, enter ``None`` for
          ``letterGradeValue`` and ``numericGradeValue``,
          and pass ``x`` as the ``specialGradeValue``.
          The ``ReturnAffectedValues`` flag determines whether to return
          student cumulative points and impacted assignment category
          grades (average and student grade)
  
          .. code-block:: python
  
              [
                  {
                      u'comment': None,
                      u'booleanGradeValue': None,
                      u'studentId': 1135,
                      u'assignmentId': 4522,
                      u'specialGradeValue': None,
                      u'returnAffectedValues': True,
                      u'letterGradeValue': None,
                      u'mode': 2,
                      u'numericGradeValue': 50,
                      u'isGradeApproved': False
                  },
                  {
                      u'comment': None,
                      u'booleanGradeValue': None,
                      u'studentId': 1135,
                      u'assignmentId': 4522,
                      u'specialGradeValue': u'x',
                      u'returnAffectedValues': True,
                      u'letterGradeValue': None,
                      u'mode': 2,
                      u'numericGradeValue': None,
                      u'isGradeApproved': False
                  },
                  {
                      u'comment': None,
                      u'booleanGradeValue': None,
                      u'studentId': 1135,
                      u'assignmentId': None,
                      u'specialGradeValue': None,
                      u'returnAffectedValues': True,
                      u'letterGradeValue': u'A',
                      u'mode': 1,
                      u'numericGradeValue': None,
                      u'isGradeApproved': False
                  }
              ]
  
          Args:
              grade_array (dict): an array of grades to save
              gradebook_id (str): unique identifier for gradebook, i.e. ``2314``
  
          Raises:
              requests.RequestException: Exception connection error
              ValueError: Unable to decode response content
  
          Returns:
              dict: dictionary containing response ``status`` and ``message``
  
          """
          log.info('Sending grades: %r', grade_array)
          return self.post(
              'multiGrades/{gradebookId}'.format(
                  gradebookId=gradebook_id or self.gradebook_id
              ),
              data=grade_array,
          )