$this->context->controller->addJS($this>_path.'views/js/mymodcomments.js'); $this->context->controller->addCSS($this->_path.'views/css/mymodcomments.css', 'all');
It makes your module compliant with the CCC option in Advanced parameters | Performance. This option is used to dynamically merge all the CSS files and JS files together.
It avoids including the same JS file several times (for example, if you need a specific jQuery UI plugin already used by another module).