def repo_def_matches_reality(juicer_def, pulp_def):
    """Compare a juicer repo def with a given pulp definition. Compute and
    return the update necessary to make `pulp_def` match `juicer_def`.

    `juicer_def` - A JuicerRepo() object representing a juicer repository
    `pulp_def` - A PulpRepo() object representing a pulp repository
    """
    return juicer.common.Repo.RepoDiff(juicer_repo=juicer_def, pulp_repo=pulp_def)