apply method
Implementation
String apply(Document document) {
if (document.doctype != null) {
_buffer.write('<!doctype');
if (document.doctype?.html != null) _buffer.write(' html');
if (document.doctype?.public != null) _buffer.write(' public');
if (document.doctype?.url != null) {
_buffer.write('${document.doctype!.url}');
}
_buffer.writeln('>');
}
_formatChild(document.root, 0);
return _buffer.toString().trim();
}