def get_version(model_instance, version):
    """
        try go load from the database one object with specific version

    :param model_instance: instance in memory
    :param version: version number
    :return:
    """
    version_field = get_version_fieldname(model_instance)
    kwargs = {'pk': model_instance.pk, version_field: version}
    return model_instance.__class__.objects.get(**kwargs)