code: func getInternetExplorerVersion(ua string) (float64, error) {
  	matches := uare.FindStringSubmatch(ua)
  
  	if len(matches) == 0 {
  		return 0.0, errors.New("Useragent is not IE")
  	}
  
  	return strconv.ParseFloat(matches[1], 64)
  }
docs: // Returns the version of Internet Explorer or a -1
  // (indicating the use of another browser).
  // http://msdn.microsoft.com/en-us/library/ms537509(v=vs.85).aspx