models.py

            }
            cache.set(cls.ALL_DEADLINES_CACHE_KEY, all_deadlines)

        return {
            course_key: all_deadlines[course_key]
            for course_key in course_keys
            if course_key in all_deadlines
        }

    @classmethod
    def deadline_for_course(cls, course_key):
        """
        Retrieve the verification deadline for a particular course.

        Arguments:
            course_key (CourseKey): The identifier for the course.

        Returns:
            datetime or None

        """
        try:
            deadline = cls.objects.get(course_key=course_key)
            return deadline.deadline
        except cls.DoesNotExist:
            return None


@receiver(models.signals.post_save, sender=VerificationDeadline)
@receiver(models.signals.post_delete, sender=VerificationDeadline)
def invalidate_deadline_caches(sender, **kwargs):  # pylint: disable=unused-argument
    """Invalidate the cached verification deadline information. """
    cache.delete(VerificationDeadline.ALL_DEADLINES_CACHE_KEY)