function readLongimport { readLong } from "https://dotland.deno.dev/x/dejs@0.10.3/vendor/https/deno.land/std/io/util.ts"; readLong(buf: BufReader): Promise<number | null>Read big endian 64bit long from BufReader Parametersbuf: BufReaderReturnsPromise<number | null>