function handleDownEvent(evt) {
  const map = evt.map;

  const feature = map.forEachFeatureAtPixel(evt.pixel, function (feature) {
    return feature;
  });

  if (feature) {
    this.coordinate_ = evt.coordinate;
    this.feature_ = feature;
  }

  return !!feature;
}
@param {import('../src/ol/MapBrowserEvent.js').default} evt Map browser event.
@return {boolean} `true` to start the drag sequence.