public function __invoke(OutputBuffer $out) { $out->write('<!DOCTYPE '); $out->writeEscaped($this->element); if ($this->hasAttribute('public')) { $out->write(' PUBLIC "')->writeEscaped($this->public)->write('"'); } if ($this->hasAttribute('system')) { $out->write(' SYSTEM "')->writeEscaped($this->system)->write('"'); } $out->write(">\n"); }