[Theme: BigBlankTheme] Parse error: syntax error, unexpected T_FUNCTION

Hey, guys!
I’m using BigBlankTheme and I’m getting this error:

Parse error: syntax error, unexpected T_FUNCTION in /home/content/23/9090823/html/extranet/hospedagem/DecoracaoBaile/wp-content/themes/BigBlankTheme/inc/filters.php on line 157

The context is this one:

function bigblank_anchor_content_h2($content) {

    // Pattern that we want to match
    $pattern = '/<h2>(.*?)<\/h2>/';

    // now run the pattern and callback function on content
    $content = preg_replace_callback($pattern,
            // function to replace the title with an id
            function ($matches) {
        $title = $matches[1];
        $slug = sanitize_title_with_dashes($title);
        return '<h2 id="' . $slug . '"><a class="anchor" href="#' . $slug . '"><i class="fa fa-link"></i></a>' . $title . '</h2>';
    }
            , $content);
    return $content;
}

Line 157 has “function ($matches) {” written in it.
Any thoughts?