import { Block } from "../../types/types";
/**
 * Immediately invokes a **block** callback and returns the time in milliseconds it takes to execute.
 */
export declare function duration(block: Block): number;
/**
 * Returns the number of elapsed milliseconds since the UNIX epoch.
 */
export declare function now(): number;
/**
 * Blocks the current thread for a given number of milliseconds.
 */
export declare function sleep(ms: number): void;