socket.close();
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        {{/if}}

        {{#if google_analytics}}
        <!-- Google Analytics Tag -->
        <script>
            var localAddrs = ["localhost", "127.0.0.1", ""];

            // make sure we don't activate google analytics if the developer is
            // inspecting the book locally...
            if (localAddrs.indexOf(document.location.hostname) === -1) {
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                })(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

                ga('create', '{{google_analytics}}', 'auto');
                ga('send', 'pageview');
            }
        </script>
        {{/if}}

        {{#if playground_line_numbers}}
        <script>
            window.playground_line_numbers = true;