import { KeyValue } from '@angular/common';
export declare function trackByRoute<T extends {
    route: string | string[];
}>(index: number, item: T): string | string[];
export declare function trackById<T extends {
    id: string | number;
}>(index: number, item: T): string | number;
export declare function trackByKey(index: number, item: KeyValue<any, any>): any;
export declare function trackByValue(index: number, value: string): string;
export declare function trackByLabel<T extends {
    label: string;
}>(index: number, value: T): string;
//# sourceMappingURL=track-by.d.ts.map