Function groupkey

docs/app/js/sanddance-app.js:115708–115712

(fields)

    };
}
function groupkey(fields) {
    return !fields || !fields.length ? function() {
        return "";
    } : fields.length === 1 ? fields[0] : multikey(fields);
}
function measureName(op, field, as) {
    return as || op + (!field ? "" : "_" + field);
}