code: func hasAcceptLanguageHeader(request *Request) (bool, string) {
  	if request.AcceptLanguages != nil && len(request.AcceptLanguages) > 0 {
  		return true, request.AcceptLanguages[0].Language
  	}
  
  	return false, ""
  }
docs: // Determine whether the given request has valid Accept-Language value.
  //
  // Assumes that the accept languages stored in the request are sorted according to quality, with top
  // quality first in the slice.