interface TransformerType ParametersoptionalI = anyoptionalO = anyPropertiesoptionalflush: TransformStreamDefaultControllerCallback<O>optionalreadableType: undefinedoptionalstart: TransformStreamDefaultControllerCallback<O>optionaltransform: TransformStreamDefaultControllerTransformCallback<I, O>optionalcancel: (reason: any) => Promise<void>optionalwritableType: undefined