interface dom.UnderlyingSourceimport { type dom } from "https://deno.land/x/evt@v2.4.17/mod.ts"; const { UnderlyingSource } = dom; Type ParametersoptionalR = anyPropertiesoptionalcancel: ReadableStreamErrorCallbackoptionalpull: ReadableStreamDefaultControllerCallback<R>optionalstart: ReadableStreamDefaultControllerCallback<R>optionaltype: undefined