/**
 * Detaches a timer from the event loop when the runtime supports it (Node), so a
 * pending acquisition timeout does not keep the process alive by itself. Browsers
 * and other runtimes return a plain number from setTimeout - nothing to do there.
 */
export declare function unrefTimer(timer: unknown): void;
/**
 * Counterpart of unrefTimer(): makes a detached timer hold the event loop again.
 */
export declare function refTimer(timer: unknown): void;
/**
 * Turns a timed out acquisition into null - the "try" flavour of acquire. Any
 * other failure (cancellation, a destroyed lock, ...) is not "the lock is busy"
 * and keeps propagating.
 */
export declare function nullOnTimeout<T>(acquisition: Promise<T>): Promise<T | null>;
export declare function isNil(value: unknown): value is null | undefined;
/**
 * A TTL is backed by a setTimeout, which fires right away for delays above
 * MAX_TIMER_DELAY_IN_MS - so larger finite values are rejected rather than
 * silently expiring at once. Infinity is fine: it means "no TTL" and needs no
 * timer.
 */
export declare function assertTtl(ttlMs: number): void;
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