yer(
                {
                    'id': 'heatmap',
                    'type': 'heatmap',
                    'source': 'activities',
                    'maxzoom': 9,
                    'paint': {
// Increase the heatmap weight based on frequency and property magnitude
                        'heatmap-weight': [
                            'interpolate',
                            ['linear'],
                            ['get', 'trackgroupentrycount'],
                            0, 0,
         