// translating line-ending \n into \r\n, and adding the final .\r\n line
// when the DotWriter is closed. The caller should close the
// DotWriter before the next call to a method on w.
//
// See the documentation for the [Reader.DotReader] method for details about dot-encoding.
func (w *Writer) DotWriter() io.WriteCloser {
	w.closeDot()
	w.dot = &dotWriter{w: w}
	return w.dot
}

func (w *Writer) closeDot() {
	if w.dot != nil {