import type { BackoffStrategy } from '../../types/options';
export declare function calculateBackoff(attempt: number, strategy: BackoffStrategy, initialDelay: number, maxDelay: number): number;
export declare function sleep(ms: number): Promise<void>;
export declare function createTimeout(ms: number, message?: string): {
    promise: Promise<never>;
    cancel: () => void;
};
export declare function withTimeout<T>(promise: Promise<T>, timeoutMs: number, timeoutMessage?: string): Promise<T>;
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