code: def mark_notifications_as_read(self, last_read_at=datetime.datetime.utcnow()):
          
          assert isinstance(last_read_at, datetime.datetime)
          put_parameters = {
              "last_read_at": last_read_at.strftime('%Y-%m-%dT%H:%M:%SZ')
          }
  
          headers, data = self._requester.requestJsonAndCheck(
              "PUT",
              "/notifications",
              input=put_parameters
          )
docs: :calls: `PUT /notifications <https://developer.github.com/v3/activity/notifications>`_
          :param last_read_at: datetime