def fedoralink_streams(obj):
    """
    Return an iterator of tuples (field, instance of TypedStream or UploadedFile)
    that were registered (via setting an instance of these classes
    to any property) with the object.

    :param obj: an instance of FedoraObject
    :return:    iterator of tuples
    """
    return getattr(obj, '__streams', {}).items()