WriteStreamEvents: {
    close: () => void;
    drain: () => void;
    error: (err: Error) => void;
    finish: () => void;
    open: (fd: number) => void;
    pipe: (src: Readable) => void;
    ready: () => void;
    unpipe: (src: Readable) => void;
} & CustomEvents

The Keys are events of the WriteStream and the values are the functions that are called when the event is emitted.