code: func (s *ScreenBuf) Clear() error {
  	for i := 0; i < s.height; i++ {
  		_, err := s.buf.Write(moveUp)
  		if err != nil {
  			return err
  		}
  		_, err = s.buf.Write(clearLine)
  		if err != nil {
  			return err
  		}
  	}
  	s.cursor = 0
  	s.height = 0
  	s.reset = false
  	return nil
  }
docs: // Clear clears all previous lines and the output starts from the top.