/**
 * Identity of one `items` entry across renders.
 *
 * The `kui-item-` prefix keeps a keyless item's position out of the namespace of
 * caller-supplied keys: without it `[{key: 1}, {}]` hands two different metrics the
 * same key, which lets the diffing move a CountUp instance from one item to the
 * other. This rule and these strings are identical in both builds.
 */
export declare function statItemKey(item: {
    key?: string | number;
}, index: number): string;