// don't subclass Error because we don't want the overhead of a stack capture
class StopException {
    arg: any;
    constructor(arg: any) {
        this.arg = arg;
    }
    get message() {
        return 'stream stopped';
    }
    get stack() {
        return 'stream stopped\n\t<no stack trace>';
    }
}

export function unwrap(ex: any) {
    return ex instanceof StopException ? ex.arg : ex;
}

export function make(arg: any) {
    return !arg || arg === true ? new StopException(arg) : arg;
}