For example in below code it seems I didn't run Leaflet but when I went to inspect webpage by DevTools I got Leaflet is running! And zoom control panel was belong to Leaflet.
I learned and used this question "openstreetmap-embedding-map-in-webpage-like-google-maps" asked in stackoverflow already.
<iframe width="400" height="600" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="https://www.openstreetmap.org/export/embed.html?bbox=51.2016004294,35.6079433209,51.5569619459,35.7819296463&layer=mapnik" style="border: 1px solid black"></iframe>
But when I changed code to different coordinate and webpage loaded again I saw map loaded perfect together with Leaflet control! Whereas I didn't write any code in page it will want to run Leaflet!