code: function request2response ( request ) {
  
      let headers = {},
          headersKeys = [],
          headersEntries = [];
  
      request.getAllResponseHeaders ().replace ( /^(.*?):\s*([\s\S]*?)$/gm, ( match, key, value ) => {
        key = key.toLowerCase ();
        headersKeys.push ( key );
        headersEntries.push ([ key, value ]);
        let prevValue = headers[key];
        headers[key] = prevValue ? `${prevValue},${value}` : value;
      });
  
      return {
        request,
        ok: ( request.status / 200 | 0 ) === 1, // 200-299
        status: request.status,
        statusText: request.statusText,
        url: request.responseURL,
        clone: () => fetch.request2response ( request ),
        text: () => Promise.resolve ( request.responseText ),
        json: () => Promise.resolve ( JSON.parse ( request.responseText ) ),
        blob: () => Promise.resolve ( new Blob ([ request.response ]) ),
        headers: {
          keys: () => headersKeys,
          entries: () => headersEntries,
          get: key => headers[key.toLowerCase ()],
          has: key => key.toLowerCase () in headers
        }
      };
  
    }
docs: /* REQUEST 2 RESPONSE