def _get_objects(source):
    """
    Returns a list of objects

    If source is lavavu.Viewer() list contains all objects
    If source is lavavu.Object() list contains that single object
    """
    if source.__class__.__name__ == 'Viewer':
        return source.objects.list
    elif not isinstance(source, list):
        return [source]
    else:
        return source
