WebStreamsUnderlyingDefaultSourceinterface UnderlyingDefaultSourceType Parameters ##R = anyProperties #optional#cancel: UnderlyingSourceCancelCallbackoptional#pull: (controller: ReadableStreamDefaultController<R>) => void | PromiseLike<void>optional#start: (controller: ReadableStreamDefaultController<R>) => anyoptional#type: undefined
interface UnderlyingDefaultSourceType Parameters ##R = anyProperties #optional#cancel: UnderlyingSourceCancelCallbackoptional#pull: (controller: ReadableStreamDefaultController<R>) => void | PromiseLike<void>optional#start: (controller: ReadableStreamDefaultController<R>) => anyoptional#type: undefined