Koha::Authorities - Koha Authority object set class
    $count = Koha::Authorities->get_usage_count({ authid => $i });
    Returns the number of linked biblio records.
    Note: Code originates from C4::AuthoritiesMarc::CountUsage.
    This is a class method, since the authid may refer to a deleted record.
    my @biblios = Koha::Authorities->linked_biblionumbers({
        authid => $id, [ max_results => $max ], [ offset => $offset ],
    });
    Returns array of biblionumbers, as extracted from the result records of
    the search engine.
    This is a class method, since the authid may refer to a deleted record.