func (tw *Writer) WriteHeader(hdr *Header) error {
	if err := tw.Flush(); err != nil {
		return err
	}
	tw.hdr = *hdr // Shallow copy of Header

	// Avoid usage of the legacy TypeRegA flag, and automatically promote
	// it to use TypeReg or TypeDir.
	if tw.hdr.Typeflag == TypeRegA {
		if strings.HasSuffix(tw.hdr.Name, "/") {
			tw.hdr.Typeflag = TypeDir
		} else {

	//	* If the UTF-8 flag is cleared, several readers simply interpret the
	//	name and comment fields as whatever the local system encoding is.
	//
	// In order to avoid breaking readers without UTF-8 support,
	// we avoid setting the UTF-8 flag if the strings are CP-437 compatible.
	// However, if the strings require multibyte UTF-8 encoding and is a
	// valid UTF-8 string, then we set the UTF-8 bit.
	//