code: func (s *Session) StdinPipe() (io.WriteCloser, error) {
  	if s.Stdin != nil {
  		return nil, errors.New("ssh: Stdin already set")
  	}
  	if s.started {
  		return nil, errors.New("ssh: StdinPipe after process started")
  	}
  	s.stdinpipe = true
  	return &sessionStdin{s.ch, s.ch}, nil
  }
docs: // StdinPipe returns a pipe that will be connected to the
  // remote command's standard input when the command starts.