// These declarations are extracted from the Typescript ESNext lib files,
// so that this module can still be used with ES5 / TS < 2.3

interface SymbolConstructor {
    /**
     * A method that returns the default async iterator for an object. Called by the semantics of
     * the for-await-of statement.
     */
    readonly asyncIterator: symbol;
}

declare var Symbol: SymbolConstructor;

interface IteratorResult<T> {
    done: boolean;
    value: T;
}

interface AsyncIterator<T> {
    next(value?: any): Promise<IteratorResult<T>>;
    return?(value?: any): Promise<IteratorResult<T>>;
    throw?(e?: any): Promise<IteratorResult<T>>;
}

interface AsyncIterable<T> {
    [Symbol.asyncIterator](): AsyncIterator<T>;
}

interface AsyncIterableIterator<T> extends AsyncIterator<T> {
    [Symbol.asyncIterator](): AsyncIterableIterator<T>;
}