code: func (conf *Config) Alias(server string) string {
  	longestMatch := ""
  	serverAlias := ""
  	for alias, serverConf := range conf.Servers {
  		if strings.HasPrefix(server, serverConf.Server) {
  			if len(serverConf.Server) > len(longestMatch) {
  				longestMatch = serverConf.Server
  				serverAlias = alias
  			}
  		}
  	}
  	return serverAlias
  }
docs: // Alias returns the alias of the server from conf that matches server, or the
  // empty string if no match. A match means the server from the config is a
  // prefix of the input server. The longest match prevails.