How to use the node-fetch-npm.Request function in node-fetch-npm

function cachingFetch (uri, _opts) {
  const opts = configureOptions(_opts)

  if (opts.integrity) {
    initializeSsri()
    // if verifying integrity, node-fetch must not decompress
    opts.compress = false
  }

  const isCachable = (opts.method === 'GET' || opts.method === 'HEAD') &&
    opts.cacheManager &&
    opts.cache !== 'no-store' &&
    opts.cache !== 'reload'

  if (isCachable) {
    const req = new fetch.Request(uri, {
      method: opts.method,
      headers: opts.headers
    })

    return opts.cacheManager.match(req, opts).then(res => {
      if (res) {
        const warningCode = (res.headers.get('Warning') || '').match(/^\d+/)
        if (warningCode && +warningCode >= 100 && +warningCode < 200) {
          // https://tools.ietf.org/html/rfc7234#section-4.3.4
          //
          // If a stored response is selected for update, the cache MUST:
          //
          // * delete any Warning header fields in the stored response with
          //   warn-code 1xx (see Section 5.5);
          //
          // * retain any Warning header fields in the stored response with

(retryHandler, attemptNum) => {
      const req = new fetch.Request(uri, reqOpts)
      return fetch(req)
        .then(res => {
          res.headers.set('x-fetch-attempts', attemptNum)

          if (opts.integrity) {
            remoteFetchHandleIntegrity(res, opts.integrity)
          }

          const isStream = req.body instanceof Stream

          if (opts.cacheManager) {
            const isMethodGetHead = req.method === 'GET' ||
              req.method === 'HEAD'

            const isCachable = opts.cache !== 'no-store' &&
              isMethodGetHead &&

function cacheDelete (uri, opts) {
  opts = configureOptions(opts)
  if (opts.cacheManager) {
    const req = new fetch.Request(uri, {
      method: opts.method,
      headers: opts.headers
    })
    return opts.cacheManager.delete(req, opts)
  }
}