code: function downloadDistantOrLoad(fileUrl, f) {
      if (!fileUrl || !_.isString(fileUrl)) {
        return f();
      }
  
      var filename = path.basename(url.parse(fileUrl).path);
  
      debug('downloading %s -> %s', fileUrl, filename);
  
      request({
        url: fileUrl
      }, function (err, resp, body) {
        if (err) {
          return f(err);
        }
  
        if (resp.statusCode < 200 || resp.statusCode >= 300) {
          return f(new Error('Invalid HTTP Status code "' + resp.statusCode + '" for "' + fileUrl + '"'));
        }
  
        fs.writeFileSync(path.resolve(process.cwd(), filename), body);
  
        f();
      });
    }
docs: Download a distant file based on `url` and then call `f`, or directly call `f`
  @param  {string|falsy} url
  @param  {function} f(err)