code: func ResolveContentType(req *Request) string {
  
  	contentType := req.Header.Get("Content-Type")
  	if contentType == "" {
  		return "text/html"
  	}
  	return strings.ToLower(strings.TrimSpace(strings.Split(contentType, ";")[0]))
  }
docs: // ResolveContentType gets the content type.
  // e.g. From "multipart/form-data; boundary=--" to "multipart/form-data"
  // If none is specified, returns "text/html" by default.