code: func isDiscreteType(s string) bool {
  	if strings.HasPrefix(s, "text") ||
  		strings.HasPrefix(s, "image") ||
  		strings.HasPrefix(s, "audio") ||
  		strings.HasPrefix(s, "video") ||
  		strings.HasPrefix(s, "application") {
  		return true
  	}
  	return false
  }
docs: // See http://tools.ietf.org/html/rfc2045
  // This doesn't include extension-token case
  // as it's handled separatly