So, this guy created a JavaScript function to change marker icon of geoJSON in mapbox map.
I tried to apply his function for my map, which is generating geoJSON from a Google spreadsheet using sheetsee.js and mapbox/leaflet. I want to change default grey icons for my own image but my re-writing attempt of his function to my map didn't work.
I'm not very skilled in JavaScript so I would be very glad for any hints what I did wrong.
