def METHOD_NAME(event):
    """Validate content_changes attribute exists in the event"""
    for value in values:
        _, diff_file = calculate_registry_diff_paths(key, subkey, arch, value)
        assert os.path.exists(diff_file), '{diff_file} does not exist'
        assert event['data'].get('content_changes')[-len(MORE_CHANGES_STR):] == MORE_CHANGES_STR, error_str