/**
 * fast O(n) non-mutating array de-duplication based on a property,
 * dot-prop path, extractor function, or full serialized value
 */
export declare function unique<ObjectType>(arr: readonly ObjectType[], property: keyof ObjectType): ObjectType[];
export declare function unique<ObjectType>(arr: readonly ObjectType[], path: string): ObjectType[];
export declare function unique<ObjectType>(arr: readonly ObjectType[], extractKey: (obj: ObjectType) => any): ObjectType[];
export declare function unique<ObjectType>(arr: readonly ObjectType[]): ObjectType[];