@classmethod
def get_exam_by_id(cls, exam_id):
    """
        Returns the Proctored Exam if found else returns None,
        Given exam_id (PK)
        """
    try:
        proctored_exam = cls.objects.get(id=exam_id)
    except cls.DoesNotExist:
        proctored_exam = None
    return proctored_exam
