code: func New() (agent.Agent, net.Conn, error) {
  	if !Available() {
  		return nil, nil, errors.New("SSH agent requested but SSH_AUTH_SOCK not-specified")
  	}
  
  	sshAuthSock := os.Getenv("SSH_AUTH_SOCK")
  
  	conn, err := net.Dial("unix", sshAuthSock)
  	if err != nil {
  		return nil, nil, fmt.Errorf("Error connecting to SSH_AUTH_SOCK: %v", err)
  	}
  
  	return agent.NewClient(conn), conn, nil
  }
docs: // New returns a new agent.Agent that uses a unix socket