Interface Transformer<I, O>

interface Transformer<I = any, O = any> {
    cancel?: (reason: any) => void | Promise<void>;
    expectedLength?: number;
    flush?: (
        controller: TransformStreamDefaultController<O>,
    ) => void | Promise<void>;
    readableType?: string;
    start?: (
        controller: TransformStreamDefaultController<O>,
    ) => void | Promise<void>;
    transform?: (
        chunk: I,
        controller: TransformStreamDefaultController<O>,
    ) => void | Promise<void>;
    writableType?: string;
}