/** `BarChart`'s tail fold, its own module so the rule is tested without a render. */
export interface FoldableBar {
    label: string;
    value: number;
}
/** Everything past the kept bars, summed: no key, so it is never a door — "everything else" is no
 *  condition a register can narrow to. */
export interface RestBar {
    label: string;
    value: number;
    rest: true;
}
/** The first `top` bars as given, then one bar summing the rest under `restLabel`. A tail of one stays
 *  itself, since a bar named "Other" hiding a single name says less than the name. The caller ranks. */
export declare function foldTail<T extends FoldableBar>(items: readonly T[], top: number | undefined, restLabel: string): (T | RestBar)[];