code: func NewDownloadError(url string, code int) error {
  	return Error{
  		Message:    fmt.Sprintf("failed to retrieve %s, response code %d", url, code),
  		Details:    nil,
  		ErrorCode:  DownloadError,
  		Suggestion: "check the availability of the address",
  	}
  }
docs: // NewDownloadError returns a new error which indicates there was a problem
  // when downloading a file