gistfile1.html

<a 
    href="http://example.com/not/existing/path/with/html/extension.html">
    
    <img 
         style="width:1px;height:1px;border:0;background:transparent" 
         src="http://example.com/not/existing/path/with/png/extension.png">
    </img>
</a>



<script>
    window["mouse_moved_detected"] = 0;
    window["$moved"] = function () {  
        if (window["mouse_moved_detected"] === 0) {
            var img = document.createElement('img');
            img.setAttribute('src','http://example.com/you-are-my-human.png');
            img.setAttribute('style','width:1px;height:1px;border:0;background:transparent');
            document.body.appendChild(img);
        }
        window["mouse_moved_detected"] =1;
    }

    window["onmousemove"] = window["$moved"];
</script>

Or even 

<script>
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</script>