Interface Transformer<I, O>

interface Transformer<I = any, O = any> {
    cancel?: (reason: any) => void | Promise<void>;
    expectedLength?: number;
    flush?: TransformerFlushCallback<O>;
    readableType?: undefined;
    start?: TransformerStartCallback<O>;
    transform?: TransformerTransformCallback<I, O>;
    writableType?: undefined;
}