|  | import { OperatorFunction, SchedulerLike, Timestamp as TimestampInterface } from '../types'; | 
|  | /** | 
|  | * Attaches a timestamp to each item emitted by an observable indicating when it was emitted | 
|  | * | 
|  | * The `timestamp` operator maps the *source* observable stream to an object of type | 
|  | * `{value: T, timestamp: R}`. The properties are generically typed. The `value` property contains the value | 
|  | * and type of the *source* observable. The `timestamp` is generated by the schedulers `now` function. By | 
|  | * default it uses the *async* scheduler which simply returns `Date.now()` (milliseconds since 1970/01/01 | 
|  | * 00:00:00:000) and therefore is of type `number`. | 
|  | * | 
|  | *  | 
|  | * | 
|  | * ## Example | 
|  | * | 
|  | * In this example there is a timestamp attached to the documents click event. | 
|  | * | 
|  | * ```ts | 
|  | * import { fromEvent } from 'rxjs'; | 
|  | * import { timestamp } from 'rxjs/operators'; | 
|  | * | 
|  | * const clickWithTimestamp = fromEvent(document, 'click').pipe( | 
|  | *   timestamp() | 
|  | * ); | 
|  | * | 
|  | * // Emits data of type {value: MouseEvent, timestamp: number} | 
|  | * clickWithTimestamp.subscribe(data => { | 
|  | *   console.log(data); | 
|  | * }); | 
|  | * ``` | 
|  | * | 
|  | * @param scheduler | 
|  | * @return {Observable<Timestamp<any>>|WebSocketSubject<T>|Observable<T>} | 
|  | * @method timestamp | 
|  | * @owner Observable | 
|  | */ | 
|  | export declare function timestamp<T>(scheduler?: SchedulerLike): OperatorFunction<T, Timestamp<T>>; | 
|  | export declare class Timestamp<T> implements TimestampInterface<T> { | 
|  | value: T; | 
|  | timestamp: number; | 
|  | constructor(value: T, timestamp: number); | 
|  | } |