declare global {
    interface Generator<T = unknown, TReturn = any, TNext = unknown> {
        /**
         * Returns the element at a specified index in a sequence.
         * @param index The zero-based index of the element to retrieve.
         * @returns The element at the specified position in the source sequence.
         */
        at(index: number): T;
        /**
         * Returns the element at a specified index in a sequence or a default value if the index is out of range.
         * @param index The zero-based index of the element to retrieve.
         * @param allow_empty Signify to return undefined if there is no item at that index.
         * @returns Undefined if the index is outside the bounds of the source sequence; otherwise, the element at the specified position in the source sequence.
         */
        at(index: number, allow_empty: "or-default"): T | undefined;
    }
    interface AsyncGenerator<T = unknown, TReturn = any, TNext = unknown> {
        /**
         * Returns the element at a specified index in a sequence.
         * @param index The zero-based index of the element to retrieve.
         * @returns The element at the specified position in the source sequence.
         */
        at(index: number): Promise<T>;
        /**
         * Returns the element at a specified index in a sequence or a default value if the index is out of range.
         * @param index The zero-based index of the element to retrieve.
         * @param allow_empty Signify to return undefined if there is no item at that index.
         * @returns Undefined if the index is outside the bounds of the source sequence; otherwise, the element at the specified position in the source sequence.
         */
        at(index: number, allow_empty: "or-default"): Promise<T | undefined>;
    }
}
export {};