/**
 * Simple implementation of context variables for Node.js
 * Provides similar functionality to Python's contextvars module
 */
/**
 * Represents a token for resetting a context variable
 */
export declare class Token<T> {
    readonly value: T;
    readonly context: ContextVar<T>;
    constructor(value: T, context: ContextVar<T>);
}
/**
 * A context variable implementation
 */
export declare class ContextVar<T> {
    private storage;
    private defaultValue;
    private identifier;
    /**
     * Create a new context variable
     * @param identifier Unique identifier for this context variable
     * @param defaultValue Optional default value
     */
    constructor(identifier: string, defaultValue?: T);
    /**
     * Get the current value of the context variable
     */
    get(): T | undefined;
    /**
     * Set a new value for the context variable
     * @param value New value
     * @returns A token that can be used to reset the variable to its previous value
     */
    set(value: T): Token<T | undefined>;
    /**
     * Reset the context variable using a token from a previous set() call
     * @param token The token from a previous set() call
     */
    reset(token: Token<T | undefined>): void;
    /**
     * Run a callback with a specific value for this context variable
     * @param value The value to set
     * @param callback The callback to run
     * @returns The result of the callback
     */
    run<R>(value: T, callback: () => R): R;
}