def METHOD_NAME(instance, reason):
    """
    Set the change reason for the historical record created from the instance.
    This method should be called before calling ``save()`` or ``delete``.
    It sets `reason` to the `_change_reason` attribute of the instance,
    that's used to create the historical record on the save/delete signals.
    https://django-simple-history.readthedocs.io/en/latest/historical_model.html#change-reason  # noqa
    """
    instance._change_reason = reason